THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 

GIFT 

From  the  Library  of 

Henry  Goldman,  Ph.D. 

1886-1972 


OTHER  WORKS  ON  PSYCHOLOGY 


THE  PSYCHIC  LIFE  OF  MICRO-ORGANISMS.     By  DR.  ALFRED  BINET. 
Pages  xii,  120.     Cloth,  75  cents.     (35.  6d.) 

ON  DOUBLE  CONSCIOUSNESS.     By  DR.   ALFRED  BINET.     Third  Edition. 
Pages  93.    Paper,  15  cents,     (gd.) 

THE  PSYCHOLOGY  OF  REASONING.     By  DR.  ALFRED  BINET.     Pages,  193. 
Cloth,  75  cents.     (35.  6d.) 

THE  SOUL  OF  MAN.   By  DR.  PAUL  CARUS.   With  152  cuts  and  diagrams.   Pages, 
xvi,  458.     Cloth,  $3.00.     (155.) 

CONTRIBUTIONS  TO  THE  ANALYSIS  OF  THE  SENSATIONS.  By  PROF. 
ERNST  MACH.    Pages,  xi,  208.    Cuts,  37.    Cloth,  $1.25.     (6s.  6d.) 

THE  PSYCHOLOGY  OF  ATTENTION.    By  PROF.  TH.  RIBOT.  Fourth  edition. 
Pages,  121.    Cloth,  75  cents.     (35.  66.) 

THE  DISEASES  OF  PERSONALITY.     By  PROF.  TH.  RIBOT.    Third  edition. 
Pages,  157.     Cloth,  75  cents.     (35.  6d.) 

THE  DISEASES  OF  THE  WILL.   By  PROF.  TH.  RIBOT.   Second  edition.   Pages, 
vi,  121.     Cloth,  75  cents.     (35.  6d.) 

THE  EVOLUTION  OF  GENERAL  IDEAS.     By  PROF.  TH.  RIBOT.     (In  prep- 
aration.)    Pages,  circa  250.     Cloth,  $1.00.     (55.) 

ON  MEMORY,  AND  THE  SPECIFIC    ENERGIES    OF   THE   NERVOUS 
SYSTEM.     By  EWALD  HERING.     Second  edition.     50  pp.   Paper,  15  cents. 

THREE  INTRODUCTORY  LECTURES  ON  THE  SCIENCE  OF  THOUGHT. 
By  PROF.  F.  MAX  MULLER.    Pages,  vi,  128.     Cloth,  75  cents.     (35.  6d.) 


THE  OPEN  COURT  PUBLISHING  COMPANY 
324  DEARBORN  ST.,  CHICAGO,  ILL. 

LONDON  :   KEGAN  PAUL,  TRENCH,  TRUBNER  &  COMPANY 


THE   PSYCHOLOGY  OF 
REASONING 

BASED  ON 

EXPERIMENTAL  RESEARCHES  IN 
HYPNOTISM 

BY 

ALFRED   BINET 

DOCTOR  OF   SCIENCE,   LAUREATE  OF  THE   INSTITUTE    (ACADEMIE   DBS   SCIENCES 
AND   ACADEMIE    DES   SCIENCES   MORALES) 

DIRECTOR  OF  THE   LABORATORY  OF   PHYSIOLOGICAL   PSYCHOLOGY   IN 
THE   SORBONNE  (HAUTES   ETUDES) 


TRANSLATED   FROM   THE   SECOND   FRENCH    EDITION 
BY   ADAM   GOWANS   WHYTE,    B.  SC. 


CHICAGO 

THE  OPEN  COURT  PUBLISHING  COMPANY 

LONDON  :  KEGAN  PAUL,  TRENCH,  TRUBNER  &  Co. 

1899 


COPYRIGHT,  1899 
BY  THE  OPEN  COURT  PUBLISHING  COMPANY 


All  rights  reserved 


K.  R.  DONNELLEY  &  SONS  COMPANY 
CHICAGO 


StacK 
Annex 


TO 

DOCTOR  CHARLES  FERE 

PHYSICIAN  IN  THE  SALPETRIERE,  BY  HIS  FRIEND 

ALFRED    BINET 


CONTENTS. 


CHAPTER  I. 
THE  DEFINITION  OF  PERCEPTION. 

PAGES 

Statement  of  the  problem. — Ancient  theory  of  proof. — Per- 
ception is  produced  by  the  cooperation  of  the  senses 
and  the  mind. — Perception  consists  of  an  association  of 
sensations  and  images. — Examples  of  illusions  of  the 
senses i 

CHAPTER  II. 
IMAGES. 

First:  The  definition  of  images.— The  indifferent  type. — 
The  visual  type.  —  The  auditory  type.  —  The  motor 
type.  Second:  The  physiological  theory  of  images. — 
Images  result  from  an  excitation  of  the  sensory  centers 
of  the  cerebral  surface  layers.  Third:  The  image 
compared  with  the  consecutive  sensation  of  sight.  .  .  10 

CHAPTER  III. 
REASONING  IN  PERCEPTION. 

First:  Properties  of  images  associated  with  sensations- 
Experiments  on  hypnotic  hallucination.  Second:  Per- 
ception results  from  an  operation  of  synthesis. — Gen- 
eric perception  and  individual  perception. — These  two 
kinds  of  perception  are  only  different  phases  of  the 
same  process. — Proofs  drawn  from  hypnotic  experi- 
ments on  systematized  anaesthesia.  Third:  Percep- 
tion is  a  reasoning. — Comparison  of  perception  with 
the  syllogism. — Helmholtz's  opinion. — The  illusion  is  a 
sophism.  Fourth :  To  what  conditions  must  an  ex- 
planation of  reasoning  be  subject? — Discussion  of 
Mr.  Spencer's  theory 56 


CHAPTER  IV. 
THE  MECHANISM  OF  REASONING. 

PAGES 

First :  The  law  of  fusion.— The  total  fusion  of  sensations 
in  Weber's  experiment. — The  partial  fusion  in  the 
zootrope. — The  partial  fusion  of  images  in  the  cases  of 
Henslow  and  of  Goethe. — The  partial  fusion  of  images 
in  the  formation  of  general  ideas. — Comparisons  drawn 
from  Gallon's  generic  images. — Physiological  expres- 
sion of  the  law  of  fusion.  Second:  The  fusion  of  sen- 
sations and  of  images. — Hypnagogic  hallucinations. — 
Toxic  hallucinations. — Voluntary  and  involuntary  illu- 
sions.— Analysis  of  a  simple  perception. — Every  per- 
ception is  an  operation  in  three  terms.  Third: 
Proofs  drawn  from  complex  perceptions.  —  New  com- 
parison between  perception  and  the  syllogism. — Theory 
of  three  images 102 

CHAPTER  V. 
CONCLUSION. 

First :  Logical  reasonings  have  the  same  mechanism  as 
perceptive  reasoning. — New  arrangement  of  the  syllo- 
gistic propositions.  Second :  Reasoning  compared  to 
a  supplementary  sense.  Third :  Reasoning  is  the 
single  type  of  all  intellectual  operations.  Fourth : 
Reasoning  is  an  organization  of  images. — Physiolog- 
ical theory  of  reasoning 158 


CHAPTER  I. 

THE   DEFINITION    OF    PERCEPTION. 

THE  important  modifications  which  were  undergone 
some  years  ago  by  the  theory  of  proof  stated  by 
Aristotle,  and  considered  for  two  thousand  years  as 
an  impregnable  truth,  are  well  known.  According 
to  the  ancient  logicians,  a  syllogism — that  is,  a 
group  of  three  propositions,  the  first  of  which  is  gen- 
eral— constitutes  a  proof.  In  the  syllogism,  "All 
men  are  mortal,  Paul  is  a  man,  therefore  Paul  is 
mortal,"  the  particular  conclusion  that  Paul,  actu- 
ally living,  is  subject  to  death,  is  proved  by  the 
major  "all  men  are  mortal,"  because  it  is  contained 
in  the  major.  Such  is  the  essence  of  proof;  the 
particular  case  is  considered  as  proved  when  it  is 
contained  in  the  general  case,  as  a  small  circle 
within  a  larger  circle;*  and  consequently  reasoning 
is  false  whenever  the  conclusion  is  not  contained 
within  the  premisses.  Stuart  Mill  was  the  first  to 
show  that  if  it  were  really  so,  if  the  conclusion  were 
contained  in  the  premisses,  reasoning  would  be 
valueless,  it  would  teach  us  nothing,  it  would  not 
be  an  instrument  of  discovery,  but  a  repetition 
under  an  altered  form  of  knowledge  already 
acquired.  In  other  words,  it  would  be  "solemn 

*Euler,  materializing  this  conception,  represented  the  syllogism  by 
three  circles  of  different  areas,  and  enclosed  one  within  another.  Lettres 
A  une  frittcesse  d'Allemagne,  ciii  et  seq. 


2      THE  PSYCHOLOGT  OF  REASONING. 

trifling."  The  one  useful  operation  consists  in 
joining  to  one  fact  a  second  fact  not  contained  in 
the  first. 

It  is  admitted,  however,  that  reasoning  supplies 
us  every  day  with  the  knowledge  of  new  truths. 
We  learn  a  new  truth  when  we  discover  that  Paul  is 
mortal,  and  we  discover  it  by  the  aid  of  reasoning, 
since,  Paul  being  yet  alive,  we  are  unable  to  learn 
it  by  direct  observation.*  Stuart  Mill  has  replaced 
the  scholastic  and  purely  nominal  theory  of  proof 
by  another  theory  which  is  entirely  positive.  He 
has  considered  it  sufficient  to  remark  that  the  major 
proposition  of  the  peripatetic  syllogism  is  not 
general,  or  at  least  that  the  general  proposition  is 
not  the  proof  of  the  conclusion.  If  we  are  justified 
in  affirming  that  Paul  is  mortal,  it  is  because 
John,  Thomas  and  the  rest  are  dead ;  it  is  because 
all  Paul's  ancestors  and  all  their  contemporaries  are 
dead.  These  numerous,  though  always  particular 
facts  are  the  real  premisses  of  reasoning,  the  real 
proofs  of  the  conclusion.  So  that  the  conclusion  is 
not  contained  in  the  premisses;  it  is  distinct  from 
them  and  adds  something  more  to  them. 

This  idea,  which  is  so  appropriate,  simple  and 
natural,  explains  how  reasoning  constitutes  a  devel- 
opment of  knowledge,  since  every  inference  leads 
from  one  particular  to  another  and  thus  adds  new 
and  previously  unobserved  facts  to  facts  already 
known.  But  this  point  of  view  has  given  rise  to  a 
problem  which  has  not  yet  been  stated  and  which 

*Mill,  Logic.  Cf.  Taine  English  Positivism,  p.  34;  Brochard  Logiqut 
de  Stuart  Mill  (Revue  philosophiqtie,  tome  xii)  and  Paul  Janet  (ibid.) 


DEFINITION  OP  PERCEPTION.  3 

has  remained  until  now  unsolved.  How  can  one 
particular  fact  prove  another  particular  fact?  The 
old  theory  of  the  syllogism  had  the  merit  of  show- 
ing, although  by  a  rough  simile,  the  manner  in 
which  the  conclusion  was  proved.  It  was  proved 
because  it  was  contained  in  a  more  general  truth, 
by  a  phenomenon  akin  to  the  incasement  of  seeds, 
and  the  whole  mental  effort  in  reasoning  was 
engaged  upon  drawing,  in  bringing  to  light  and 
extracting  these  conclusions  from  the  premisses, 
which  enclosed  them  like  large  envelopes.  But  as 
soon  as  the  terms  can  no  longer  be  considered  as 
containing  one  another,  and  the  circles  of  Euler 
cease  to  represent  the  operations  of  the  mind,  it 
becomes  necessary  to  find  a  new  theory  of  proof. 

The  mental  process  in  the  case  of  external  per- 
ception belongs  to  the  class  of  unconscious  reason- 
ings. But  little  importance  need  be  attached  to  this 
characteristic ;  for  there  is  really  only  one  method 
of  reasoning,  and  the  study  of  unconscious  reasoning 
leads  us  to  conclusions  which  are  applicable  to  all 
kinds  of  ratiocination.  These  conclusions  are: 
that  the  fundamental  element  of  the  mind  is  the 
image ;  that  reasoning  is  an  organization  of  images, 
determined  by  the  properties  of  the  images  them- 
selves, and  that  the  images  have  merely  to  be 
brought  together  for  them  to  become  organized, 
and  that  reasoning  follows  with  the  inevitable 
necessity  of  a  reflex.  In  order  to  demonstrate  this 
general  conclusion  as  clearly  as  possible,  we  shall 
systematically  avoid  all  the  side  issues  to  which  a 
subject  such  as  this  frequently  gives  rise. 


4      THE  PSTCHOLOGT  OF  REASONING. 

The  word  perception  is  vague  enough.  Medical 
men  usually  confound  perception  with  sensation ; 
they  say  of  many  a  patient  that  he  has  lost  the 
perception  of  red  or  of  blue,  while  they  are  really 
speaking  of  the  sensation  of  these  colours.  Hume 
called  all  states  of  consciousness  perception.  In 
modern  times,  certain  psychologists,  M.  Janet 
among  others,  defined  perception  as  the  act  by 
which  the  mind  distinguishes  and  identifies  sensa- 
tions. We  shall  adopt  in  this  book  the  definition 
given  by  English  psychologists*  and  we  shall  des- 
ignate as  perception  the  act  which  takes  place 
when  our  mind  enters  into  relation  with  external 
and  present  objects. 

Perception  is,  from  the  common-sense  point  of 
view,  a  simple  act;  it  is  a  passive  state,  a  kind  of 
receptivity.  To  perceive  an  external  object,  our 
hand  for  example,  is  simply  to  be  conscious  of 
the  sensations  which  the  object  produces  on  our 
organs.  Some  examples  will,  however,  suffice  to 
show  that  in  every  act  of  perception,  the  mind  con- 
stantly adds  to  the  impressions  of  the  senses. 
Everybody  knows  that  we  can  hear  the  words  of  a 
familiar  song  clearly,  while  we  are  frequently  unable 
to  distinguish  those  of  an  unknown  song,  even  when 
both  songs  are  sung  by  the  same  voice,  a  fact  which 
plainly  shows  the  share  due  to  the  mind.  Instead 
of  our  seeking  examples,  proofs  may  be  produced. 
Wundt  and  his  pupils  have  made  several  experi- 
ments on  this  subject.  An  unknown  sketch,  an 
engraving,  is  illumined  by  a  series  of  electric  sparks, 

*Bain,  The  Emotions  and  The  Will,  p.  583. 


DEFINITION  OF  PERCEPTION.  5 

and  it  is  noted  that  the  perception  of  this  sketch, 
while  very  much  confused  during  the  first  sparks, 
becomes  more  and  more  distinct.  The  impression 
produced  on  the  retina  is  nevertheless  the  same  at 
each  flash ;  but  the  perception  becomes  each  time 
more  complete  and  precise,  by  the  help  of  the 
recollection  formed  in  the  mind  by  the  preceding 
perceptions.*  One  might  add  some  more  examples 
drawn  from  the  perception  of  space,  the  complex 
and  secondary  character  of  which  has  been  known 
to  us  since  the  days  of  Berkeley. 

Perception  is  therefore  a  mixed  state,  a  cerebro- 
sensory  phenomenon  produced  by  an  action  on  the 
senses  and  a  reaction  of  the  brain.  It  may  be  com- 
pared to  a  reflex,  the  centrifugal  period  of  which, 
instead  of  manifesting  itself  externally  in  move- 
ments, would  be  expended  internally  in  awakening 
associations  of  ideas.  The  discharge  follows  a 
mental  channel  instead  of  a  motor  one. 

But  psychology  demands  a  larger  measure  of 
precision.  It  is  not  enough  to  say  that  in  every 
perception  there  are  sensations  and  something  more 
which  the  mind  adds  to  the  sensations.  What  is 
the  nature  of  this  addition?  This  question  may  be 
best  answered  by  the  study  of  the  illusions  of  the 
senses.  It  is  now  known  that  in  such  illusions  the 
error  is  not  to  be  imputed  to  the  sensitive  organ,  as 
the  ancients  believed,  but  to  the  mind.  An  illusion 
is  a  mixed  phenomenon,  composed,  like  the  sen- 
sory perception  of  which  it  is  a  counterfeit,  by  the 
co-operation  of  the  senses  and  the  mind.  The 

*Experiments  cited  by  M.  Lachelier  (Revue  philosophique,  February 
1885.) 


6      THE  PSTCHOLOGT  OF  REASONING. 

sensory  impressions  are  always  what  they  ought  to 
be,  the  nature  of  the  external  excitant  and  the  state 
of  the  sensitive  organ  being  given.  The  error  lies 
in  the  co-operation  of  the  mind,  in  the  interpreta- 
tion of  the  sensations.  Now,  the  examination  of 
some  illusions  will  be  sufficient  to  show  in  what  this 
co-operation  of  the  mind  consists,  and  what  is  to 
be  understood  by  an  interpretation  of  sensations. 

One  of  my  friends,  now  a  university  professor, 
has  related  to  me  this  story  of  his  youth.  One 
evening,  when  he  was  walking  alone  in  a  country 
broken  up  by  large  woods,  he  perceived,  in  a  clear- 
ing, a  large  fire  lighted.  Then,  immediately  after, 
he  saw  an  encampment  of  gypsies  around  this  fire. 
There  they  were,  with  their  bronzed  faces,  lying  on 
the  ground  and  engaged  in  cooking.  The  night 
was  dark,  and  the  place  very  lonely.  Our  young 
man  was  afraid,  he  lost  his  head  completely,  and, 
brandishing  the  stick  he  held  in  his  hand,  he  dashed 
furiously  into  the  gypsies'  camp.  A  moment  after 
he  was  in  the  middle  of  a  pond,  convulsively 
clasping  a  tree-trunk  with  his  arms,  and  feeling  the 
chill  of  water  which  rose  as  far  as  his  knees.  Then 
he  saw  a  will-o'-the-wisp  flickering  on  the  surface 
of  the  pond;  it  was  this  shining  spot  which  had 
been  the  starting  point  of  his  sensory  illusion. 

I  owe  the  following  account  to  another  of  my 
friends,  Dr.  G.  A.  One  day  when  he  was  ascending 
the  Rue  Monsieur-le-Prince  in  Paris,  he  thought  he 
read  on  the  glass  door  of  a  restaurant  the  two 
words  verbascum  thapsus.  This  is  the  scientific 
name  for  one  of  the  scrophulariaceae  of  our  country, 


DEFINITION  OF  PERCEPTION.  7 

which  is  commonly  called  "bouillon  blanc."  My 
friend  had  passed  the  preceding  days  in  preparing 
for  an  examination  in  natural  history;  his  memory 
was  still  surcharged  with  all  those  Latin  names 
which  render  the  study  of  botany  so  tiresome. 
Surprised  at  the  inscription  which  he  had  just  per- 
ceived, he  retraced  his  steps  in  order  to  verify  its 
accuracy,  and  then  he  saw  that  the  tariff  of  the 
restaurant  bore  the  simple  word  "bouillon."  This 
word  had  suggested  "bouillon  blanc"  to  his  mind, 
and  this  in  turn  had  suggested  verbascum  tJiapsus. 

These  are  two  cases  in  point.  They  show  us  the 
composition  of  the  element  which  the  mind  adds 
to  sensation  in  the  perception  of  external  objects. 
This  element  must  bear  a  remarkable  resemblance 
to  sensations,  since  it  is  indistinguishable  from 
them.  The  young  man  who  traverses  a  forest 
really  believes  that  he  sees  before  him  a  band  of 
gypsies;  all  this  phantasmagoria  comes  from  a 
brain  rendered  delirious  by  fear;  it  is  a  psycholog- 
ical phenomenon  which,  whatever  its  nature,  is 
very  nearly  related  to  sensation,  since  it  does  duty 
for  it.  Similarly  Dr.  A.  believes  he  sees  written  on 
the  door  of  a  restaurant  words  which  exist  only 
in  his  mind ;  for  this  confusion  to  be  possible  it  is 
necessary  once  again  that  the  mind  should  have  the 
power  of  producing,  of  manufacturing  and  of  objec- 
tivizing  certain  simulacra  which  in  a  striking  manner 
resemble  sensations. 

For  several  years  past  these  pseudo-sensations 
have  attracted  the  special  attention  of  psycholo- 
gists. They  are  called  representations  in  Germany. 


8      THE  PSYCHOLOGY  OF  REASONING. 

In  France  the  prevailing  term  is  images;  it  is 
this  which  we  shall  use. 

A  definition  of  sensory  perception  will  form  the 
conclusion  of  this  short  introduction :  Perception 
is  the  process  by  which  the  mind  completes,  with 
the  accompaniment  of  images,  an  impression  of 
the  senses. 

We  shall  begin  by  studying  these  images.  Their 
role  is  of  the  greatest  importance;  in  many  cases 
they  almost  entirely  efface  the  consciousness  of  the 
sensations  which  have  given  rise  to  them.  It  is  this 
fact  which  justified  Helmholtz  in  comparing  the 
perception  of  external  objects  to  an  interpretation 
of  signs.  The  sensations  are  the  signs;  our  mind 
takes  no  more  note  of  them  than  is  necessary  to 
learn  their  meaning.  The  perception  of  the  exter- 
nal world  is  like  the  reading  of  a  book;  pre-occu- 
pied  by  the  meaning,  the  reader  forgets  the  written 
characters  immediately  after  they  are  seen.  This 
neglect  of  the  sensations  is  proved  by  several  inter- 
esting examples.  We  usually  see  trees  and  distant 
forests  in  green,  with  the  lines  of  the  hills  in  gray- 
blue;  the  gray-blue  is  to  us  the  colour  of  distances. 
But  if,  altering  the  conditions  of  observation,  we 
view  the  landscape  from  beneath  our  arms  or  be- 
tween our  legs,  the  colours  immediately  lose  their 
relations  with  the  distances  of  the  objects;  they 
appear  pure,  with  their  true  shades.  We  then 
recognize  that  the  gray-blue  of  the  distances  is  often 
a  fairly  deep  violet,  that  the  green  of  the  vegetation 
shades  off 'imperceptibly  into  this  violet  through  a 


DEFINITION  OF  PERCEPTION.  9 

greenish  blue,  and  so  on.  (Helmholtz.)  The  dif- 
ference arises  from  the  fact  that,  under  these  con- 
ditions, the  sensations  are  valued  as  such,  and  not 
as  signs,  which  are  merely  important  because  of  the 
images  which  they  excite. 

Let  us  proceed  to  the  study  of  these  images. 


CHAPTER  II. 

IMAGES. 

I 

WE  do  not  here  intend  to  give  a  complete  theory 
of  Images;  such  an  attempt  seems  premature.  The 
question  is  not,  in  several  respects,  mature.  But  we 
are  obliged  to  devote  several  pages  to  the  study  of 
these  interesting  phenomena;  for  the  knowledge  of 
the  nature  of  images  cannot  fail  to  throw  light  upon 
the  problem  of  the  mechanism  of  reasoning.  In 
short,  images,  along  with  sensations,  constitute  the 
materials  of  all  intellectual  operations;  memory,  rea- 
soning, imagination  are  acts  which  consist,  in  an  ulti 
mate  analysis,  of  grouping  and  co-ordinating  images, 
in  apprehending  the  relations  already  formed  be- 
tween them,  and  in  reuniting  them  into  new  rela- 
tions. "Just  as  the  body  is  a  polypus  of  cells,"  said 
M.  Taine,  "the  mind  is  a  polypus  of  images." 

It  is  not  long  since  an  apparent  agreement  was 
reached  regarding  the  psychological  nature  of 
images.  Some  ancient  authors,  it  is  true,  had 
already  seen  what  has  escaped  a  number  of  our  con- 
temporaries. Aristotle  said  that  one  could  not 
think  without  a  sensible  image.  But  many  intelli- 
gent minds  were  loath  to  admit  that  material  signs 
were  essential  to  the  exercise  of  thought.  This 
seemed  to  them  to  be  a  concession  to  materialism. 


IMAGES.  1 1 

In  1865,  at  the  time  when  a  great  discussion  on 
hallucinations  was  taking  place  among  the  members 
of  the  "Societe  medico-psychologique,"  the  phi- 
losopher Gamier  and  some  eminent  alienists,  such  as 
Baillarger,  Sandras  and  others,  still  held  that  an  im- 
passable chasm  separates  the  conception  of  an  object 
which  is  absent  or  imaginary — otherwise  called  an 
image — and  the  actual  sensation  produced  by  a 
present  object ;  that  the  two  phenomena  differ  not 
only  in  degree,  but  in  kind,  and  that  they  resemble 
each  other  no  more  than  "the  body  and  the 
shadow."  It  is  interesting  to  compare  the  opinion 
of  these  writers  with  the  replies  which  Galton 
obtained  previously  from  a  large  number  of  scientific 
men,  when  he  began  his  great  inquiry  into  Mental 
Images  (Mental  Imagery).  He  asked,  in  a  question- 
naire which  he  circulated,  whether  one  was  able  to 
represent  absent  objects  mentally  by  a  kind  of 
internal  vision — he  took  a  thoroughly  English  ex- 
ample :  the  appearance  of  breakfast  when  served — 
and  if  this  entirely  subjective  representation  had 
common  characteristics  with  the  external  vision. 
While  uneducated  people,  women,  furnished  him 
with  very  interesting  replies  on  the  nature  of  mental 
vision,  the  scientific  men  to  whom  he  appealed 
refused  to  believe  in  this  faculty,  which  seemed  to 
them  to  be  merely  a  figure  of  speech. 

Things  have  changed  since  that  time.  Psy- 
chologists and  physiologists — notably  M.  Taine  and 
Mr.  Galton* — have  endeavored  to  determine  the 

*Taine,  On  Intelligence,  Part  i,  book  II;  Galton,  Inquiries  into  Human 
Faculty  and  its  Development,  p.  83. 


12     THE  PSTCHOLOGT  OF  REASONING. 

nature  of  images,  their  seat  in  the  brain,  and  their 
relations  with  sensations.  They  have  shown  that 
each  image  is  a  sensation  spontaneously  revived, 
generally  simpler  and  more  feeble  than  the  original 
impression,  but  capable  of  acquiring,  under  given 
conditions,  an  intensity  so  great  as  to  make  us  be- 
lieve that  the  external  object  is  still  seen.  The 
complete  demonstration  of  these  truths,  which  now- 
adays have  finally  become  trite,  will  be  found  in 
special  works;  they  are  now  only  useful  in  filling 
out  second-rate  psychological  treatises. 

We  may  remark  in  passing  that  this  theory  of 
the  image  is  in  no  way  materialistic ;  it  connects  the 
image  with  the  sensation,  making  the  former  a  pre- 
served and  reproduced  sensation.  Now,  what  is  a 
sensation?  It  is  not  a  material  fact;  it  is  a  con- 
scious state,  like  an  emotion  or  a  desire.  If  one  is 
tempted  to  see  a  material  fact  in  the  sensation,  it  is 
because  it  has  a  very  apparent  physiological  correl- 
ative, the  excitation  produced  by  the  exterior 
object  upon  the  organ  of  the  senses  and  transmitted 
to  the  brain.  But  it  is  known  that  all  mental 
phenomena  are  accompanied  by  a  physiological 
phenomenon.  That  is  the  law.  The  sensation 
and  the  image  do  not  differ  in  this  respect  from 
other  states  of  consciousness. 

The  development  of  images  is  very  variable.  It 
varies,  according  to  Galton,  with  race.  The 
French,  he  says,  appear  to  possess  this  gift,  as 
attested  by  their  talent  for  organizing  ceremonies 
and  fetes,  their  aptitude  for  strategy,  and  the 


IMAGES.  13 

clearness  of  their  language;  figurcz-vous  is  an  ex- 
pression which  is  often  met  with  in  French.  Age 
and  sex  appear  likewise  to  be  of  importance.  The 
power  of  visualizing  is  more  developed  among  chil- 
dren than  among  adults,  among  women  than  among 
men.  There  are  probably  some  children,  says 
Galton,  who  pass  years  of  difficulty  in  distinguishing 
between  the  objective  and  the  subjective  world — 
that  is  to  say,  between  sensations  and  images. 

But  it  is  important,  first  of  all,  to  distinguish  the 
different  kinds  of  images,  which  are  as  numerous  as 
the  different  kinds  of  sensations.  Each  sense  has 
its  images,  these  being  therefore  visual,  auditory, 
tactile,  motor,  etc.  We  are  able,  when  we  exercise 
our  memory  on  an  object,  to  cumulatively  employ 
every  kind  of  image,  or  to  have  recourse  to  only  a 
single  kind.  Every  person  has  his  own  habits, 
depending  on  the  nature  of  his  organism. 

We  must  therefore  distinguish  several  varieties 
of  individuals,  several  types.*  Common  experience 
made  this  distinction  long  ago  as  far  as  memory  is 
concerned;  it  is  recognized  that  there  is  often,  in 
the  same  man,  a  natural  inequality  in  the  different 
forms  of  memory ;  a  certain  person  recollects  sounds 
best  of  all,  another  colours,  a  third  figures  and  dates, 
etc.  Pathology  has  proved  the  independence  of 
these  partial  memories,  showing  that  some  may 
disappear  and  leave  the  others  intact.  Thus  it  is 
that  a  man  may  lose  the  single  memory  for  words, 
or  forget  a  single  language,  or  be  deprived  solely  of 

*The  idea  of  distinguishing  several  sensory  types  is  due  to  M.  Charcot, 
who  has  explained  it  in  his  lectures  on  Aphasia,  at  the  Salpetriere. 


14  THE  PSrCHOLOGT  OF  REASONING. 

his  musical  memory,  etc.  M.  Ribot  has  made 
a  very  complete  study  of  these  partial  amnesias. 

We  are  thus  prepared  to  study  the  sensory 
types.  It  must  be  understood  that  this  inequality 
of  the  kinds  of  memory  depends  upon  a  more  gen- 
eral cause,  the  inequality  of  the  kinds  of  images; 
that  those  individuals  who  have,  for  example,  a 
good  visual  memory,  are  those  in  whom  visual 
images  predominate;  that  consequently  it  is  not 
merely  the  visual  memory  that  is  most  conspicu- 
ous in  them,  it  is  also  the  visual  reasoning,  the 
visual  imagination,  etc.  One  may  call  these  people 
visuels.  There  are  thus  several  types,  characterized 
by  the  predominance  of  one  order  of  images  in  the 
mental  routine. 

One  of  the  most  common  types  is  certainly  the 
indifferent  type.  In  those  who  belong  to  this  class 
no  one  kind  of  image  is  more  developed  than  the 
others.  When  they  wish  to  recall  a  person,  they 
see  in  their  minds  the  form  and  colour  of  his  figure 
as  clearly  as  they  hear  the  sound  of  his  voice.  The 
visual  memory  is  equal  to  the  auditory  memory ; 
these  two  memories  may  besides  be  very  well  de- 
veloped, or  may  have  remained  rudimentary,  but  in 
every  case  they  are  of  equal  value.  The  indifferent 
also,  in  his  reasonings,  in  his  imaginings,  in  his 
dreams,  employs  the  different  kinds  of  images  in 
equal  proportions.  This  is  perhaps  the  most  frequent 
type ;  it  is  the  normal  type,  the  approach  to  which 
must  be  expected,  since  it  infers  a  harmonious 
development  of  all  the  sensory  functions. 

Alongside  the  indifferent  type  must  be  placed  the 


IMAGES.  15 

visual  type,  which  is  also  very  common.  A  large 
number  of  persons  make  use  almost  exclusively  of 
visual  images;  if,  for  example,  they  think  of  a 
friend,  they  see  his  figure,  but  do  not  hear  his 
voice ;  when  they  wish  to  learn  a  page  of  a  book 
by  heart,  they  impress  upon  their  memory  the 
visual  image  of  the  page  with  its  characters,  and  in 
reciting  it  by  heart  they  have  this  image  before 
their  mind's  eye,  and  read  it.  When  they  recall 
an  air,  they. see  distinctly,  by  the  same  process,  the 
notes  of  the  score.  But  it  is  not  only  their  memory 
which  is  visual;  all  their  other  faculties  are.  When 
they  reason,  or  when  they  exercise  their  imagina- 
tion, they  employ  visual  images  alone.  The  exclu- 
sive development  of  the  mind  in  a  single  sense  per- 
mits the  visuel  to  perform  operations  which  are 
feats  of  skill.  There  are  chess  players  who,  with 
their  eyes  shut  and  their  head  turned  to  the  wall, 
carry  on  a  game  of  chess.  It  is  clear,  says 
M.  Taine,  that  at  each  move  the  appearance  of  the 
whole  chess  board,  with  the  arrangement  of  the 
various  pieces,  is  present  to  them  as  in  an  internal 
mirror;  otherwise  they  would  be  unable  to  foresee 
the  consequences  of  the  move  which  has  been 
made  against  them  and  the  move  which  they  wish 
to  make.  Two  friends  who  possessed  this  faculty 
often  played  mental  chess  games  together  while 
walking  on  the  quays  and  in  the  streets.  Galton 
tells  us  that  a  person  of  his  acquaintance  was  in  the 
habit  of  calculating  with  an  imaginary  calculating 
rule,  the  several  parts  of  which  he  read  mentally 
according  as  they  were  necessary  for  each  of  his 


1 6     THE  PSrCHOLOGT  OF  REASONING. 

problems.  Many  orators  have  their  manuscript 
placed  mentally  before  their  eyes  when  they  speak 
in  public.  Certain  painters,  designers  and  sculptors, 
after  they  have  attentively  studied  a  model,  are 
able  to  make  a  copy  of  it  from  memory.  Horace 
Vernet  and  Gustave  Dor£  possessed  this  faculty. 
A  painter  once  copied  from  memory  a  Martyre  de 
Saint-Pierre  by  Rubens  with  an  accuracy  which 
deceived  the  connoisseurs.  An  English  painter, 
mentioned  by  Wigan,  painted  a  portrait  standing, 
after  only  one  sitting  from  the  model.  He  held 
the  man  in  his  mind,  placed  him  mentally  on  the 
chair,  and  every  time  that  he  looked  at  the  chair 
he  saw  the  person  seated.  Little  by  little  his  mind 
became  confused;  he  affirmed  that  the  model  had 
actually  sat,  and  finally  he  became  insane. 

Such  is  the  danger  of  this  hypertrophy  of  the 
visual  image.  Those  who  possess  such  an  intense 
visualization  are  half  under  the  influence  of  halluci- 
nation, and  it  is  a  hundred  to  one  that  the  halluci- 
nation will  some  day  become  complete.  We  may 
add  that  very  probably  visuels  are  specially  predis- 
posed to  hallucinations  of  the  sight,  and  conse- 
quently to  the  forms  of  delirium  of  which  visual 
hallucinations  are  the  symptom.  According  to  this 
theory,  a  pure  visucl  can  never  become  a  persecute', 
because  in  the  persecution  delirium  only  the  hallu- 
cinations of  hearing  are,  in  general,  according  to 
Lasegue's  observation,  met  with.  The  persecute' 
does  not  see  his  persecutors,  he  merely  affects  to 
hear  them.  We  shall  see  later  that  there  is  an 
objective  sign  whereby  we  may  recognize  whether 


IMAGES.  17 

an  individual  does  or  does  not  belong  to  the  visual 
type. 

Persons  who  belong  to  the  pure  visual  type  are 
exposed,  besides,  to  a  serious  danger;  when  they 
happen  to  lose,  by  one  of  those  accidents  which 
pathologists  are  at  present  earnestly  studying,  their 
faculty  of  mental  vision,  they  lose  everything  at  the 
same  time.  It  is  impossible,  or  at  least  extremely 
difficult,  for  them  to  make  use  of  the  other  images, 
which  have  remained  in  a  rudimentary  state.  The 
indifferent  type  is  much  better  situated ;  what  is 
lost  on  the  score  of  sight,  for  example,  is  regained  on 
the  score  of  hearing;  substitutions  are  made  be- 
tween the  different  kinds  of  images. 

M.  Charcot  has  related,  in  one  of  his  clinical 
lectures,  an  interesting  pathological  case,  bringing 
to  light  the  existence  of  the  visual  type  and  show- 
ing the  kind  of  disorder  which  occurs  among  these 
subjects  when  they  lose  their  faculty  of  mental 
vision.  We  reproduce,  with  a  little  abridgment, 
the  observation  published  by  M.  Bernard  (Progres 
medical,  July  21,  1883). 

"M.  X.,  a  merchant  at  A ,  was  born  at 

Vienna;  he  is  a  very  well  educated  man;  he  knows 
German,  Spanish  and  French  perfectly,  as  well  as 
Latin  and  Greek  classics.  Until  the  beginning  of 
the  affection  which  brought  him  to  Professor  Char- 
cot,  he  read  the  works  of  Homer  at  sight.  He 
knew  the  first  book  of  the  Iliad  well  enough  not  to 
hesitate  in  continuing  a  passage  the  first  verse  of 
which  had  been  said  before  him. 

"His  father,  professor  of  Oriental  languages  at 


1 8  THE  PSTCHOLOGT  OF  REASONING. 

L ,  likewise  possessed  one  of  the  most  remark- 
able of  memories.  It  was  the  same  with  his 
brother,  professor  of  law  at  W—  — ,  with  one  of  his 
sisters,  a  distinguished  painter;  his  own  son,  aged 
seven  years,  already  knows  the  most  insignificant 
historical  dates  wonderfully  well. 

"M.  X.  enjoyed  until  a  year  ago  an  equally 
remarkable  memory.  Like  that  of  his  father  and  of 
his  son,  it  was  principally  a  visual  memory.  His 
mental  vision  gave  him,  as  soon  as  he  wished,  the 
representation  of  the  features  of  persons,  the  form 
and  the  colour  of  things  with  as  much  distinctness 
and  intensity,  he  asserts,  as  the  reality  itself. 

"If  he  were  looking  for  a  fact,  a  number  men- 
tioned in  his  voluminous  correspondence,  which 
was  written  in  several  languages,  he  found  them 
again  immediately  in  the  letters  themselves,  which 
appeared  to  him  in  their  exact  purport,  with  the 
smallest  details,  irregularities  and  erasures  in  their 
wording. 

"When  he  repeated  a  lesson  at  school,  or  a  piece 
from  a  favorite  author  later,  two  or  three  readings 
had  fixed  the  page  in  his  memory  with  its  lines  and 
its  letters,  and  he  repeated  it  while  mentally  reading 
the  desired  passage,  which,  as  soon  as  he  wished, 
appeared  before  him  with  great  distinctness. 

"M.  X.  has  traveled  much.  He  was  fond  of 
sketching  the  landscapes  and  views  which  had 
struck  him.  He  drew  fairly  well.  His  memory 
gave  him,  whenever  he  wished,  the  most  accurate 
panoramas.  If  he  wished  to  recollect  a  conversa- 
tion, to  bring  back  a  speech  or  a  spoken  word,  the 


IMAGES.  19 

place  of  the  conversation,  the  physiognomy  of  the 
speaker,  in  a  word,  the  whole  scene,  a  detail  of  which 
was  all  he  sought,  appeared  to  him  in  its  entirety. 

"  M.  X.  's  auditory  memory  was  always  wanting,  or 
at  least  it  never  appeared  to  be  other  than  a  second- 
ary matter  with  him.  He  has  never  had,  among 
others,  any  taste  for  music. 

"A  year  and  a  half  ago  he  became  worried  about 
some  important  debts  the  payment  of  which  seemed 
uncertain  to  him.  He  lost  his  appetite  and  his  sleep ; 
his  fears  were  not  justified  by  the  event.  But  the 
emotion  had  been  so  intense  that  it  did  not  subside, 
as  he  hoped,  and  one  day  M.  X.  was  suddenly 
startled  to  find  that  he  had  considerably  changed. 
At  first  there  was  complete  disorder;  there  was 
thereafter  a  strong  contrast  between  his  new  state 
and  the  old.  For  a  while  M.  X.  believed  that  he 
was  threatened  with  insanity,  so  many  things  around 
him  seemed  new  and  strange.  He  had  become  nerv- 
ous and  irritable.  The  visual  memory  of  forms  and 
colours  had  in  every  case,  as  he  was  not  slow  to  per- 
ceive, completely  disappeared,  and  this  knowledge 
had  the  effect  of  reassuring  him  on  his  mental  con- 
dition. He  found,  besides,  little  by  little,  that  he 
was  able,  by  employing  other  forms  of  memory,  to 
continue  to  successfully  direct  his  commercial  affairs. 
He  has  now  resigned  himself  to  the  new  situation, 
the  difference  between  which  and  M.  X.  's  original 
situation,  described  above,  may  be  readily  shown. 

"Every  time  M.  X.  returns  to  A ,  which  he 

frequently  leaves  on  business,  it  seems  to  him  that 
he  is  entering  an  unknown  town.  He  looks  at  the 


20  THE  PSTCHOLOGT  OF  REASONING. 

monuments,  streets  and  houses  with  astonishment, 
as  when  he  arrived  there  for  the  first  time.  Paris, 
which  he  has  frequented  as  often,  produces  in  him 
the  same  effect.  Memory  returns,  however,  little 
by  little,  and  at  last  he  again  discovers,  readily 
enough,  his  route  in  the  labyrinth  of  streets.  When 
asked  to  give  the  description  of  the  principal  square 

in  A ,  of  its  arcades,  of  its  statues,  he  says:  'I 

know  that  that  exists,  but  I  can  imagine  nothing 
of  it,  and  can  tell  you  nothing  about  it.'  He  had 
often  before  drawn  the  roadstead  of  A —  — ;  now  he 
vainly  tries  to  reproduce  the  principal  lines,  which 
completely  escape  him. 

"His  visual  memory  of  his  wife  and  children  is 
powerless.  He  recognizes  them  at  first  no  better 

than  he  does  the  roadstead  and  streets  of  A , 

and  even  by  the  time  when,  in  their  presence,  he 
succeeds  in  doing  so,  he  seems  to  see  new  traits 
and  new  characteristics  in  their  physiognomy. 

"He  does  not  go  so  far  as  to  forget  his  own  per- 
son. Recently,  in  a  public  gallery,  he  found  him- 
self barring  the  passage  of  a  person  to  whom  he  was 
about  to  make  his  apologies,  and  who  was  only  his 
own  image  reflected  by  a  mirror. 

"During  our  conversation,  M.  X.  complained 
strongly  of  several  returns  of  the  visual  loss  of  col- 
ours. He  seemed  more  concerned  about  this  than 
about  the  rest.  'My  wife  has  black  hair;  I  am 
perfectly  sure  of  that.  It  is  a  complete  impossibil- 
ity for  me  to  find  that  colour  again  in  my  memory,  as 
complete  as  that  of  imagining  her  person  and  her 
features.' 


IMA  GES.  2 1 

"This  visual  amnesia  also  extends  to  the  things 
of  childhood  as  well  as  to  more  recent  things.  M.  X. 
no  longer  knows  anything  visually  of  the  pater- 
nal mansion.  This  memory  was  formerly  very  near 
to  him,  and  he  evoked  it  often. 

"The  examination  of  the  eye  gave  completely 
negative  results.  M.  X.  suffers  from  a  myopia  as 
strong  as  -/D.  Here  is  also  the  result  of  the  ex- 
amination of  M.  X.'s  ocular  functions  made  with 
the  greatest  care  by  Dr.  Parinaud,  in  the  ophthalmic 
room  at  the  hospital:  No  ocular  lesions  or  func- 
tional troubles  objectively  apparent,  if  there  be  not 
always  a  slight  enfeeblement  of  the  chromatic  sensi- 
bility, affecting  all  colours  equally. 

"We  may  add  that  no  somatic  symptoms  pre- 
ceded, accompanied  or  followed  this  loss  of  the 
visual  memory  observed  in  our  patient. 

"M.  X.  is  now  obliged,  like  almost  everybody 
else,  to  open  the  copies  of  his  letters  so  as  to  find 
the  information  he  wants  there ;  and  he  must,  like 
all  the  world,  peruse  them  before  he  comes  to  the 
place  he  is  looking  for. 

"He  recollects  no  more  than  a  few  of  the  first 
verses  of  the  Iliad,  and  in  the  reading  of  Homer, 
Virgil  or  Horace  he  no  more  than  begins,  so  to 
speak,  to  feel  his  way. 

"He  utters,  half -aloud,  the  figures  which  he  is 
adding,  and  he  is  no  longer  able  to  proceed  save  by 
small  partial  calculations. 

"When  he  recalls  a  conversation,  when  he 
wishes  to  recollect  a  thing  said  in  his  presence,  he 
plainly  feels  that  he  must  now,  and  not  without 


22  THE  PSYCHOLOGY  OF  REASONING. 

effort,  consult  his  auditory  memory.  The  words, 
tJic  recollected  speeches,  seem  to  him  to  resound  in  his 
ear,  a  sensation  which  is  quite  new  to  him. 

"Since  this  great  change  occurred  in  him  M.  X. 
has  been  obliged,  in  order  to  learn  anything  by 
heart,  a  series  of  phrases  for  example,  to  read  these 
phrases  aloud  several  times,  and  thus  influence  his 
ear,  and  later,  when  he  repeats  the  thing  he  has 
learned  he  has  a  very  clear  sensation  of  internal 
hearing  preceding  the  delivery  of  the  words,  a 
sensation  which  was  previously  unknown  to  him.* 

"An  interesting  detail  is  that,  in  his  dreams 
M.  X.  no  longer  has,  as  before,  the  visual  representa- 
tion of  things.  The  representation  of  words  alone 
remains  to  him,  and  these  belong  almost  exclusively 
to  the  Spanish  language." 

The  auditory  type  seems  to  us  to  be  rarer  than 
the  preceding  types;  it  is  recognized  by  the  same 
distinctive  characteristics.  Persons  of  this  type 
conceive  all  their  recollections  in  the  language  of 
sound;  in  order  to  recall  a  passage  they  impress 
upon  their  minds,  not  the  visual  aspect  of  the  page, 
but  the  sound  of  their  words.  Reasoning  is  with 
them  auditory,  as  is  memory;  for  example,  when 
they  perform  a  mental  addition,  they  verbally 
repeat  the  names  of  the  figures,  and  in  some  way 
add  the  sounds,  without  having  a  representation  of 
the  written  sign.  Their  imagination  also  takes  an 
auditory  form.  "When  I  write  a  scene,"  said 
Legouve  to  Scribe,  "7  hear;  you  see;  at  each 

*I  am  now  obliged,  writes  M.  X.  .  .  to  say  to  myself  the  things  -which  I 
•wish  to  retain  in  my  memory,  -while  formerly  I  had  merely  to  photograph 
them  by  my  sight. 


IMAGES.  23 

phrase  which  I  write,  the  voice  of  the  person  who  is 
speaking  strikes  my  ear.  You,  who  are  the  theatre 
itself,  your  actors  walk,  act  before  your  eyes;  I  am 
the  listener  and  you  the  spectator."  "Nothing 
could  be  more  correct, "  said  Scribe.  "Do  you  know 
where  I  am  when  I  write  a  piece?  In  the  middle 
of  the  parterre."  (Cited  by  Bernard  in  De 
r  apliasie,  p.  50.)  It  is  plain  that  the  pure  auditif, 
seeking  to  develop  only  one  of  his  faculties,  is  capa- 
ble of  accomplishing,  like  the  visuel,  regular  feats 
of  memory;  for  example,  Mozart  noting  down  from 
memory,  after  two  hearings,  the  Miserere  of  the 
Sixtine  Chapel ;  deaf  Beethoven  composing  huge 
symphonies  and  repeating  them  to  himself  inter- 
nally. By  way  of  compensation,  the  auditif,  like 
the  visuel,  is  exposed  to  serious  dangers;  for  if  he 
lose  his  auditory  images,  he  is  left  resourceless;  he 
is  completely  bankrupt. 

It  is  possible  that  those  who  are  subject  to  hallu- 
cinations of  the  hearing  and  those  individuals  who 
are  attacked  by  the  delirium  of  persecution  belong 
to  the  auditory  type ;  and  that  the  predominance 
of  one  order  of  images  creates  a  predisposition  to  a 
corresponding  order  of  hallucinations — and  perhaps 
also  of  delirium. 

We  have  yet  to  speak  of  the  motor  type,  which 
is  perhaps  the  most  interesting  of  all,  and  by  far  the 
least  known.  People  who  belong  to  this  type,  the 
moteurs,  as  they  are  called,  make  use  of,  in  memory, 
reasoning  and  all  their  other  intellectual  operations, 
images  derived  from  movement.  To  fully  under- 
stand this  important  point,  it  will  be  sufficient  to 


24  THE  PSYCHOLOGY  OF  REASONING. 

remember  that  all  "our  perceptions,  in  particular 
the  important  ones,  those  of  sight  and  touch,  imply 
as  integral  elements  movements  of  the  eye  or  the 
members;  and  that  if  movement  is  an  essential 
element  when  we  see  an  object  really,  it  must  play 
the  same  role  when  we  see  it  ideally."*  For  exam- 
ple, the  complex  impression  of  a  ball,  which  is  there 
in  our  hand,  is  the  resultant  of  optical  impressions 
of  the  eye,  impressions  of  touch,  of  muscular 
adjustments  of  the  eye,  of  movements  of  the  fingers, 
and  of  the  muscular  sensations  which  result  there- 
from, f  When  we  think  of  the  ball,  this  idea  must 
comprise  the  images  of  these  muscular  sensations} 
as  it  comprises  the  images  of  the  sensations  of  sight 
and  of  touch.  Such  is  the  motor  image.  That  its 
existence  was  not  earlier  recognized  is  due  to  our 
knowledge  of  the  muscular  sense  being  compara- 
tively recent;  it  was  never  discussed  in  ancient 
psychology,  where  the  number  of  the  senses  was 
reduced  to  five. 

There  are  people  who  remember  a  drawing  bet- 
ter when  they  have  followed  the  outlines  with  their 
finger.  Lecoq  de  Boisbaudran  made  use  of  this 
means  in  his  teaching  of  art,  in  order  to  accustom 
his  pupils  to  draw  from  memory;  he  made  them 
follow  the  outlines  of  the  figures  with  a  pencil  held 
at  a  distance  in  the  hand,  thus  obliging  them  to 
associate  the  muscular  with  the  visual  memory. 
Galton  relates  a  curious  corroborative  fact:  "Colo- 

•Ribot,  The  Diseases  of  the  Will,  p.  5.  (Chicago:  The  Open  Court 
Pub.  Co.) 

|W.  James  has  shown  that  these  muscular  sensations  are  the  afferent 
sensations  which  proceed  from  contracted  muscles,  stretched  ligaments, 
compressed  articulations,  etc.  The  Feeling  of  Effort,  Boston,  1880. 


IMAGES.  25 

nel  Moncrieff, "  he  says,  "informs  me  that 
young  Indians  occasionally  came  to  his  quarters, 
and  that  he  found  them  much  interested  in  any 
pictures  or  prints  that  were  put  before  them.  On 
one  of  these  occasions  he  saw  an  Indian  tracing  the 
outline  of  a  print  from  the  Illustrated  News  very 
carefully  with  the  point  of  his  knife.  The  reason 
that  he  gave  for  this  odd  manoeuvre  was  that  he 
would  remember  the  better  how  to  carve  it  when 
he  returned  home."*  In  this  case  the  motor 
image  of  the  movements  was  intended  to  reinforce 
the  visual  image ;  this  young  savage  was  a  motcur. 

Should  this  process  not  be  generalized  and  ap- 
plied to  education?  It  is  probable  that  a  child 
would  learn  to  read  and  write  more  quickly  if  he 
were  trained  to  trace  the  characters  at  the  same  time 
as  they  were  spelt.  The  belief  that  it  is  impossible 
to  do  two  things  well  at  the  same  time  is  a  prejudice. 
By  making  reading  and  writing  proceed  together, 
the  two  memories,  visual  and  motor,  are  constrained 
to  associate  and  to  aid  one  another  like  two  horses 
harnessed  to  the  same  carriage. 

The  motor  image  enters  as  an  essential  element 
into  a  large  number  of  mental  combinations, 
although  its  presence  is  often  unsuspected.  The 
memory  of  a  movement  is  based  upon  motor 
images;  when  these  images  are  destroyed,  the 
memory  of  the  movement  is  lost,  and,  which  is 
more  curious,  in  certain  cases  even  the  aptitude  to 
execute  it.  Pathology  supplies  us  with  several  ex- 
amples of  this,  in  motor  aphasia,  in  agraphia,  etc. 

*Galton,  Inquiries  into  Human  Faculty  and  its  Development,  p.  106. 


26  THE  PSYCHOLOGY  OF  REASONING. 

Let  us  take  the  case  of  agraphia.  An  educated  man, 
knowing  how  to  write,  loses  all  at  once,  suddenly, 
as  a  result  of  cerebral  accidents,  the  faculty  of  writ- 
ing; his  arm  and  his  hand  are  in  no  way  paralyzed, 
and  yet  he  is  unable  to  write.  Upon  what  does 
this  powerlessness  depend?  He  himself  says:  upon 
his  no  longer  knowing.  He  has  forgotten  how  he 
must  proceed  in  order  to  trace  the  letters,  he  has 
lost  the  memory  of  the  movements  to  be  executed, 
he  no  longer  possesses  the  motor  images  which 
when  formerly  he  set  himself  to  write  directed  his 
hand.  It  is  possible,  thanks  to  hynotism,  to  vary 
the  examples  of  these  systematized  paralyses,  which 
affect  only  a  particular  system  of  movements,  leav- 
ing the  others  intact  and  the  arm  completely  free. 
It  is  in  this  way  that  we  may  make  a  hypnotized 
subject  lose,  by  suggestion,  the  faculty  of  accomp- 
lishing a  definite  act,  such  as  smoking,  sewing, 
embroidering,  laughing,  etc.  We  have  often  in- 
sisted on  the  advantage  which  hypnotism  offers  in 
this  respect,  in  the  study  of  the  majority  of  motor 
and  sensitive  troubles.1* 

Other  patients,  struck  by  verbal  blindness,  make 
accurate  use  of  these  motor  images  in  order  to  make 
up  for  what  they  lack  in  another  way.  We  collect 
all  these  examples  because  the  subject  is  not  popular- 
ly known ;  it  will  be  useful  if  we  combine  several  facts 
scattered  here  and  there,  and  endeavour  to  make  a 
synthesis  of  them.  An  individual  afflicted  by  ver- 
bal blindness  is  no  longer  able  to  succeed  in  reading 
the  characters  placed  before  his  eyes,  although  his 

*Binet,  and  Fer€,  Les  faralysies  far suggestion  (.Revue  scientifique,  July, 
1884). 


IMAGES.  27 

vision  may  be  intact  or  sufficiently  good  to  permit 
of  perusal.  The  loss  of  the  faculty  of  reading  is 
sometimes  the  only  trouble  which  exists  at  a  certain 
time ;  the  patient  who  is  thus  maimed  may,  how- 
ever, succeed  in  reading,  but  indirectly,  by  means 
of  a  roundabout  method  which  he  often  discovers 
for  himself;  all  he  has  to  do,  in  order  to  understand 
the  meaning  of  the  characters,  is  to  trace  them  with 
his  finger.  What  happens  in  a  case  such  as  this? 
By  what  mechanism  can  he  establish  a  substitution 
between  the  eye  and  the  hand  ?  The  motor  image 
gives  us  the  key  to  the  problem.  That  the  patient 
is  able  to  read,  in  some  way,  with  his  fingers,  is 
because  he  receives,  in  describing  the  characters,  a 
certain  number  of  muscular  impressions  which  are 
those  of  writing.  We  may  say  at  a  stretch,  the 
patient  reads  while  writing  (Charcot) ;  that  is,  the 
graphic  motor  image  suggests  the  meaning  of  the 
characters  according  to  the  same  standard  as  the 
visual  image. 

We  have  just  seen  the  place  which  the  motor 
image  occupies  in  the  sphere  of  sight  and  in  the 
sphere  of  movement.  Its  role  is  no  less  important 
in  the  sphere  of  hearing.  There  are  persons  in 
whom  the  mental  representation  of  a  sound  is 
always  a  motor  image  of  articulation.  M.  Strieker 
is  one  of  the  number.  He  it  is  who  was  the  first 
to  make  the  particulars  of  this  subject  known.  The 
following  are  the  principal  proofs  he  has  employed : 
"When  I  form,"  he  says,  "the  image  of  the  letter 
P,  the  same  sensation  is  produced  in  my  lips  as  if  I 
were  reallv  about  to  articulate  it.  If  I  think  of  the 


28  THE  PSYCHOLOGY  OF  REASONING. 

letter  R,  I  experience  the  same  sensation  at  the 
base  of  the  tongue  as  if  I  expressly  wished  to  utter 
that  consonant.  In  my  opinion,  this  sensation 
constitutes  the  essence  of  the  image  of  sound." 
Such  is  the  first  proof;  the-  second  is  that  it  is  im- 
possible to  imagine  a  letter  at  the  same  time  as  the 
muscles  used  in  articulating  it  are  given  a  fixed 
position  which  prevents  them  from  entering  into 
action.  One  cannot  think  of  the  letter  B,  which 
is  a  labial,  while  the  mouth  is  held  wide  open,  a 
position  which  hinders  the  movement  of  the  lips. 
Finally,  the  third  proof  is  that  one  cannot  have  at 
one  and  the  same  time  the  representation  of  two 
letters,  A  and  U  for  example,  when  the  muscles 
which  are  employed  in  articulating  them  are  the 
same.  "Whoever,"  he  says,  "is  capable  of  simul- 
taneously producing,  by  constraining  his  breathing 
for  a  sufficient  interval,  the  sounds  A  and  U,  is 
justified  in  regarding  my  theory  as  null  and  void. 
I  need  do  no  more  than  appeal  to  the  judgment 
of  the  reader.  Such  a  simultaneity  is  absolutely 
impossible,  since  the  very  muscles  employed  in  the 
formation  of  the  auditory  image  of  A  must  also  be 
used  in  forming  that  of  U.  Now,  I  could  not 
innervate  them  simultaneously — as  would  neverthe- 
less be  necessary— in  one  manner  for  the  sound  A 
and  in  another  manner  for  the  sound  U." 

To  make  this  quite  clear,  it  must  be  remarked 
that  M.  Strieker's  experiments  are  in  no  way  con- 
cerned with  the  visual  image  of  letters ;  it  is  evident, 
for  example,  that  one  may  graphically  represent  to 
one's  self  the  letter  B  while  the  mouth  is  kept  open; 


IMAGES.  29 

but  that  is  not  the  question.  M.  Strieker  meant, 
by  the  representation  of  a  letter,  the  auditory  rep- 
resentation alone,  that  which  constitutes  internal 
speech.  This  author  maintains  that  what  is  taken 
to  be  an  auditory  image,  that  is  to  say,  an  enfee- 
bled repetition  of  the  sound  which  is  heard  when  a 
given  letter  is  pronounced,  has  nothing  to  do  with  the 
sense  of  hearing;  it  is  a  motor  image,  a  beginning  of 
an  articulation  which  stops  before  reaching  its  end. 

Objections  have  been  raised  to  M.  Strieker's 
work  by  M.  Paulhan,  who  entirely  disputes  the 
facts  advanced.  M.  Paulhan  has  performed  all  the 
experiments  crucis  laid  down  by  M.  Strieker,  and  he 
states  that  he  can  do  a  large  number  of  the  things 
which  M,  Strieker  declares  to  be  impossible.  "I 
find,"  he  says,  "that  I  am  able,  while  pronouncing 
the  letter  A  aloud,  to  represent  to  myself  mentally 
the  series  of  vowels,  and  even  to  imagine  an  entire 
phrase ;  I  conclude  from  this  that,  since  under  these 
conditions — that  is  to  say,  the  muscles  used  in  pro- 
nouncing A  being  innervated — the  motor  image  of 
the  other  vowels  cannot  be  produced,  I  conclude 
from  this,  I  say,  that  the  image  of  the  other  vowels 
and  of  the  other  words  is  not,  at  least  for  me  and 
those  who  feel  like  me,  a  motor  image. ' ' 

What  does  this  difference  of  opinion  prove? 
Simply  that  the  two  observers  have  different  images 
and  belong  to  different  types.  M.  Strieker  belongs, 
for  a  certainty,  to  the  motor  type;  he  is  so  to  this 
degree  that  he  does  not  even  conceive  that  others 
might  be  constituted  differently.  It  is  by  virtue  of 
the  exaggeration,  the  abnormality  which  the  phe- 


30     THE  PSTCHOLOGT  OF  REASONING. 

nomenon  presents  in  him,  that  he  has  discovered  a 
fact  which  no  one  had  noticed.  But  as  we  have 
always  the  defects  of  our  qualities,  M.  Strieker 
completely  ignores  the  role  which  sight  and  hearing 
play  in  the  recollection  of  words,  and  he  attributes 
everything  to  the  motor  image.  He  even  goes  as 
far  as  to  make  this  astonishing  observation :  "I 
have  not  yet  met  any  one  who  could  have  said  to 
me  that  he  imagined  the  contents  of  a  newspaper 
article  with  the  printed  characters  which  composed 
it.  One  may  remember  several  articles  by  heart, 
several  phrases,  but  as  words  which  are  pronounced 
internally,  and  not  as  graphic  images  of  words 
which  might  be  read  in  the  memory,  as  on  the 
printed  page."  It  would  be  difficult,  one  will 
admit,  to  write  anything  more  false.  All  the 
visuels,  and  they  are  many,  do  what  M.  Strieker 
declares  to  be  impossible.  This  is  a  good  illustra- 
tion of  the  remark  that  everybody,  in  philosophiz- 
ing, gives  us  the  theory  of  his  own  nature. 

On  the  other  hand,  it  is  probable  that  M.  Paul- 
han  and  those  who  feel  like  him  belong  to  the 
purely  auditory  or  the  indifferent  type.  Such  is 
the  very  simple  solution  which  may  reasonably  be 
given  to  this  little  debate.* 

II. 

The  theory  of  the  Image  was  at  the  point  at 
which  we  have  just  left  it  when  M.  Fere  and  my- 
self approached  the  study  of  this  phenomenon.!  We 

*Stricker,  Le  langage  et  la  musique,  Alcan.  i8S;;  for  the  discussion 
with  M.  Paulhan,  see  Revue  jhilosophique,  years  1883  and  1884,  Passim. 

\Theorie  des  hallucinations  (Revue  scientifique,  January,  1885). 


IMAGES.  31 

introduced  experiments  in  hypnotism,  which 
enabled  us  to  settle  a  number  of  undecided  ques- 
tions; from  these  experiments,  which  we  shall 
briefly  recapitulate,  there  follows  a  consequence 
which  is  important  in  connection  with  the  seat  of 
images.  Hitherto  we  have  refrained  from  defining 
this  seat ;  and  we  might  yet  with  advantage  main- 
tain, while  adhering  to  what  has  preceded,  that  the 
image  is  simply  localized  "in  the  soul"  and  pos- 
sesses, as  has  been  said,  a  purely  spiritual  existence. 
But  this  is  not  the  case ;  there  exist  precise,  proved 
and  incontestable  facts  which  demonstrate  that  the 
image — or  rather  the  corresponding  nervous  process 
—has  a  fixed  seat  in  the  brain,  that  this  seat  is  the 
same  for  the  image  and  the  sensation,  and  that, 
finally,  to  sum  the  whole  matter  up  in  a  single 
formula,  the  image  is  a  phenomenon  which  results 
from  an  excitation  of  the  sensory  centres  of  the  cor- 
tex. 

We  shall  therefore  expound  what  might  be  called 
a  physiological  theory  of  the  image,  or  at  least,  if 
the  phrase  is  too  pretentious,  a  series  of  experi- 
ments which  treat  of  the  physiology  of  the  image. 
These  experiments  were  made  in  M.  Charcot's  clin- 
ical laboratory  at  the  Salpetriere,  on  young  hys- 
terico-epileptic  girls,  who  were  completely  hypnot- 
ized according  to  the  ordinary  and  frequently 
described  processes.* 

We  know  that  is  possible  to  produce  hallucina- 
tions of  all  the  senses  in  hypnotized  subjects  during 

*For  further  details,  I  refer  the  reader  to  the  work  which  I  have  written 
in  collaboration  with  Dr.  Fer6:  Le  magnetisme  animal  {Bibliotheque 
tfientifique  Internationale,  Alcaii,  Paris). 


32  THE  PSTCHOLOGT  OF  REASONING. 

certain  stages  of  the  trance,  and  especially  during 
somnambulism.  These  induced  hallucinations 
form  one  of  the  most  familiar  psychical  symptoms 
of  hypnotism.  The  voice  is  generally  used  to  pro- 
duce them.  When  the  subject  is  suitably  prepared, 
when  the  right  moment  has  come,  we  have  only  to 
say  to  him,  authoritatively,  "There  is  a  serpent," 
for  him  to  see  it  crawling  before  him.  This  hallu- 
cination is  subjective,  personal  to  the  subject,  and 
consequently  may  be  easily  feigned ;  but  it  presents 
so  many  objective  characters  that  its  existence  can- 
not be  doubted,  at  least  in  the  cases  in  which  these 
characters  are  present.  Therefore  we  shall  not  stop 
to  discuss  the  hypothesis  of  simulation  again;  in 
proportion  as  we  proceed  with  our  exposition,  the 
reality  of  the  phenomenon  will  be  proved. 

How  can  the  experimenter  excite  hallucinations 
by  speech?  How  can  he  make  the  subject  come 
to  see  a  serpent  or  a  bird  merely  by  what  he  says  to 
him?  Can  this  phenomenon  be  explained?  And  is 
there  any  analogous  phenomenon  in  the  normal  life 
of  a  wide-awake  individual?  Such  are  the  questions 
which  a  psychologist  should,  in  view  of  these  expe- 
rimental hallucinations,  put  to  himself.  We  raise 
these  questions  because,  while  investigating  them, 
we  shall  show  how  experiments  in  hallucination 
may  be  useful  to  the  theory  of  Images. 

When,  during  a  conversation  with  a  wide-awake 
person,  we  speak  to  him  of  the  colour  red,  and  he 
understands  the  meaning  of  that  word,  we  raise  an 
image  in  his  mind,  the  image  of  red,  by  virtue  of 
the  association  which  has  been  established  by  educa- 


IMAGES.  33 

tion  between  the  word  and  the  idea;  but  this 
created  image  is  generally  very  feeble,  very  pale; 
after  being  barely  caught  sight  of,  it  vanishes,  like 
a  "super"  who  has  merely  crossed  the  stage.  The 
word  has  excited  in  the  wide-awake  person  a  vision 
of  red,  but  a  short,  rapid  and  defective  vision.  Dif- 
ferent circumstances  may  render  the  vision  more 
durable  and  more  powerful,  even  during  the  waking 
state.  Here  is  a  striking  example  of  this.  It  is 
related  that  on  the  evening  of  the  execution  of 
Marshal  Ney,  several  people  were  assembled  in  a 
Bonapartist  room;  suddenly  the  door  opened  and 
the  servant,  mistaking  the  name  of  one  of  the 
arrivals,  who  was  called  M.  Mar£chal  Ain£,  an- 
nounced aloud:  "Monsieur  le  Marechal  Ney." 
At  these  words  a  thrill  of  fear  ran  through  the 
gathering,  and  those  who  were  present  have  since 
related  that  for  an  instant  they  distinctly  saw  in 
M.  Mar6chal,  Ney  himself  advancing  in  person  into 
the  middle  of  the  room.  Here  we  touch  upon  the 
suggested  hallucination,  if  the  phenomenon  does  not 
actually  belong  to  that  class.  The  hallucinations 
which  are  produced  in  the  hypnotic  state  by  the 
voice  of  the  experimenter  do  not  possess  a  different 
mechanism.  The  voice  of  the  experimenter  excites 
the  auditory  centre  of  his  subject,  and  this  centre, 
once  awakened,  transmits  its  excitation  to  the  visual 
centre,  by  virtue  of  pre-established  dynamical  asso- 
ciations. Then  the  visual  image  arises  and  ob- 
trudes itself  with  so  much  the  more  energy  that  it 
reigns  alone  in  the  consciousness  of  the  patient;  the 
part  of  his  brain  which  is  excited  is  the  only  part 


34     THE  PSYCHOLOGY  OF  REASONING. 

which  reacts,  and  it  consequently  gives  its  maxi- 
mum. But  let  us  put  aside  these  particular  condi- 
tions which  make  the  image  evoked  so  intense  and 
transform  it  into  a  hallucination.  What  is  import- 
ant for  us  to  show  is  the  fact  that  the  phenomenon 
of  suggested  hallucination  in  hypnotism  is  not  iso- 
lated from  ordinary  intellectual  processes;  that,  on 
the  contrary,  its  germ  exists  in  the  images  which 
people  our  mind  during  the  waking  state,  and  that 
hallucination  may  definitely  be  made  use  of  as  an 
exaggeration  of  the  image  in  studying  its  properties. 
The  first  fact  to  which  we  shall  call  attention, 
from  the  point  of  view  of  the  physiology  of  the 
image,  is  the  effect  of  achromatopsia  or  color  blind- 
ness. It  is  known  that  a  large  number  of  hysterical 
subjects  display  an  insensibility  which  extends  over 
one  entire  half  of  the  body  and  divides  it  vertically 
into  two  parts;  this  hemi-anaesthesia  is  usually 
accompanied  by  more  or  less  pronounced  sensory 
anaesthesias;  on  the  insensible  side  the  hearing  is 
enfeebled,  the  nostril  smells  odours  with  difficulty, 
and  one-half  of  the  tongue  cannot  distinguish  the 
tastes  of  the  foods  which  are  placed  upon  it.  But 
what  really  interests  us  most  is  the  state  of  the  eye. 
This  organ  shares  with  the  others  in  the  insensibil- 
ity. In  most  cases  a  concentric  contraction  of  the 
visual  field  is  observed,  and  at  the  same  time  the 
loss  or  enfeeblement  of  one  or  several  sensations  of 
colour,  in  other  words,  achromatopsia.  This  loss  of 
colours  occurs  according  to  a  definite  order.  The 
colour  which  is  first  lost  is  violet ;  green  is  second ; 
this  order  is  constant  in  all  patients.  In  the  case 


IMAGES.  35 

of  the  other  colours,  two  classes,  which  occur  almost 
equally  often,  must  be  laid  down ;  in  the  one,  the 
patients  lose  violet,  green,  red,  yellow  and  blue 
successively:  in  the  other,  the  red  and  blue  are 
inverted,  and  the  series  reappears  thus:  violet, 
green,  blue,  yellow  and  red. 

It  is  interesting  to  investigate  the  influence 
which  achromatopsia  might  exercise  upon  coloured 
hallucinations  which  are  suggested  during  hypnot- 
ism. M.  Richer  was  the  first  to  observe  that  if 
only  the  achromatoptic  eye  of  a  hypnotized  subject 
is  kept  open,  it  is  impossible  to  suggest  any  coloured 
hallucinations  to  her  by  the  medium  of  that  eye. 
If  the  patient  have  lost  the  colour  violet,  it  is  impos- 
sible to  make  violet  enter  into  her  hallucinations, 
and  so  on.  Here  are  some  examples  of  this: 

"I?ar,  in  the  waking  state,  is  achromatoptic  in 
her  right  eye.  Keeping  her  left  eye  closed,  we 
make  her  see  a  flock  of  birds.  To  our  questions  on 
the  colour  of  their  plumage,  she  replies  that  they  are 
all  white  or  gray.  If  we  insist,  assuring  her  that 
she  is  mistaken,  she  maintains  that  she  sees  only 
white  or  gray  birds.  But  the  state  of  affairs  alters 
if  at  that  moment  we  open  her  left  eye,  whether 
her  right  eye  be  closed  or  not;  she  is  immediately 
enraptured  with  the  variety  and  brilliance  of  their 
plumage,  in  which  all  the  different  colours  are  com- 
bined. 

"This  experiment  has  been  varied  in  many 
ways.  Closing  her  left  eye  we  show  her  Harlequin, 
and  she  describes  him  as  all  covered  with  gray, 
white  or  black  squares.  Polichinelle  is  likewise 


36  THE  PSrCHOLOGT  OF  REASONING. 

dressed  in  white  or  gray.  "  It  is  original, ' '  she  says, 
"but  it  is  not  pretty."  Immediately  upon  open- 
ing her  left  eye  the  notion  of  colour  reappears,  and 
Harlequin  and  Polichinelle  appear  to  her  in  motley, 
as  they  are  commonly  represented."* 

The  same  rule  appears  to  extend,  as  I  have 
shown,  to  the  spontaneous  hallucinations  of  insan- 
ity. I  have  observed  a  hysterical  lunatic,  who  was 
a  patient  of  Dr.  Magnan's  at  the  Asile  Sainte- 
Anne,  continually  possessed  with  the  image  of  a 
man  dressed  in  red.  This  woman  was  hemi-anaes- 
thetic  and  achromatoptic  in  the  left  eye;  when  her 
right  eye  was  closed  she  continued  to  perceive  her 
hallucination  with  her  left  eye,  but  the  man  who 
appeared  to  her  was  no  longer  red ;  he  was  gray, 
and  seemed  as  if  surrounded  by  a  mist. 

Thus  blindness  in  one  colour  obstructs  the  hallu- 
cination— that  is  to  say,  the  image  of  that  same 
colour.  How  may  this  be  explained?  Very  simply, 
if  we  consider  achromatopsia  as  a  cerebral  phenom- 
enon, as  a  functional  disturbance  of  the  cells  of  the 
cortex  affected  by  the  sensation  of  colours.  Since 
this  functional  disturbance  places  the  same  obstacle 
in  the  way  of  the  hallucination  as  in  that  of  the 
sensation  of  a  given  colour,  it  seems  probable  that 
the  sensation  and  the  image  employ  the  same  kind 
of  nervous  elements.  In  other  words,  the  halluci- 
nation would  take  place  in  the  centres  where  sense 
impressions  are  received ;  it  would  result  from  an 
excitation  of  the  sensory  centres.  What  is  said  of 
the  hallucination  applies  directly  to  the  image. 

*P.  Richer,  Etudes  cliniqucs  stir  rhystero  epilepsie,  p.  708,  2nd.  edit. 


IMAGES.  37 

It  will  perhaps  be  objected  that  there  are  some 
hypnotized  hysterical  subjects  in  whom  achroma- 
topsia does  not  prevent  the  suggestion  of  coloured 
hallucinations.  But  it  seems  to  us  to  be  easy  to 
explain  this  departure  from  the  rule.  We  shall 
confine  ourselves  to  remarking  that  achromatopsia  in 
hysterical  subjects  depends  upon  hemi-anaesthesia; 
that  this  loss  has  nothing  definite  about  it ;  that  it 
is  less  a  paralysis  than  a  paresia,  an  inactivity  of  the 
nervous  elements.  These  elements  no  longer 
respond  to  the  call  of  their  normal  stimulus,  col- 
oured light ;  but  there  is  nothing  astonishing  in  their 
reacting  when  they  are  attacked  from  another  side, 
by  an  excitation  which  comes  from  the  auditory 
centres  and  is  nothing  else  than  verbal  suggestion. 
Other  facts  may  be  given  to  corroborate  the 
localization  of  the  image  in  the  sensory  centre.  A 
large  number  of  observations  collected  by  M. 
Fere  show  that  a  constant  connection  exists  be- 
tween the  special  sensibility  of  the  eye  and  the  gen- 
eral sensibility  of  its  integuments.  When  a  cereb- 
ral lesion  causes  sensitive  disturbances  in  the 
integuments  of  the  eye,  visual  disturbances,  such  as 
achromatopsia  and  concentric  or  lateral  shrinking  of 
the  visual  field  are,  on  looking  a  little  closely  into 
the  matter,  likewise  met  with.  In  hysterical  hemi- 
anaesthesia,  a  connection  is  also  observed  between 
the  sensibility  of  the  conjunctiva  and  of  the  cornea 
and  the  special  sensibility  of  the  organ ;  these  two 
sensibilities  are  always  affected  to  a  similar  degree. 
The  interpretation  of  these  and  many  other  facts 
too  numerous  to  be  repeated  here,  has  led  M.  Fer£ 


38  THE  PSYCHOLOGY   OF  REASONING. 

to  the  following  conclusion:  that  there  exist  in 
undetermined  regions  of  the  encephalon  sensitive 
centres  which  are  common  to  the  organs  of  the 
senses  and  to  the  integuments  which  surround 
them.* 

Now,  if  we  carefully  examine  all  that  happens 
when  a  visual  hallucination  is  produced  in  a  hyp- 
notized subject,  we  see  that  in  many  cases  the  hal- 
lucination modifies  the  sensibility  of  the  external 
membranes  of  the  eye.  In  the  cataleptic  state,  the 
conjunctiva  and  the  cornea,  outside  the  pupillary 
field,  are  generally  insensible;  but  as  soon  as  the 

visual  hallucination  has  been  produced,  in  P 

for  example,  the  sensibility  of  the  external  mem- 
branes returns  to  the  condition  in  which  it  exists 
during  the  waking  state ;  the  membranes  cannot  be 
touched  by  a  foreign  body  without  exciting  palpe- 
bral  reflexes,  f  With  the  said  M the  hallucina- 
tion continues  for  several  minutes  on  awakening, 
always  producing  a  dysaesthesia  of  the  membranes 
of  the  eye,  which  lasts  exactly  as  long  as  the  hallu- 
cination. With  the  said  Wit ,  the  unilateral 

hallucination  produces  a  slight  pain  in  the  eye 
which  is  alone  hallucinated;  "I  feel  as  if  there  were 
sand  in  that  eye,"  says  the  patient.  These  three 
observations  seem  to  show  that  the  visual  hallu- 
cination, or,  in  a  more  general  way,  the  visual 
image,  implicates  the  centre  of  vision. 

But  we  have  not  yet  approached  the  most  inter- 

*Ch.  F£re,  Troubles  fonctionnels  de  la  vision,  pp.  149,  i$o  and  151. 

tCh.  Fere,  Les  hysteriqncs  hypnotiques  comme  sujets  (Texperimtnta,- 
tion,  etc.  (Arch,  de  neurologie,  1883,  t.  VI,  p.  122). 


IMAGES.  39 

esting  observations  in  this  class  of  ideas.  We  have 
yet  to  speak  of  the  chromatic  phenomena  produced 
by  hallucinations  of  the  sight. 

Let  us  first  of  all  recall  three  physiological 
experiments  which  may  easily  be  performed  with- 
out much  apparatus.  In  the  first  experiment  we 
take  a  card  divided  into  two  equal  parts,  the  one 
red,  the  other  white,  and  having  at  its  centre  a 
point  for  the  purpose  of  fixing  the  sight ;  if  we  gaze 
at  this  point  for  several  moments,  we  see  a  green 
colour  appearing  on  the  white  half.  This  is  the 
chromatic  contrast.*  In  the  second  experiment  we 
gaze  fixedly  upon  a  little  red  cross  with  a  black  spot 
at  its  centre ;  if  we  then  turn  our  eyes  to  a  sheet  of 
white  paper  bearing  a  black  spot,  we  immediately 
see  a  green  cross  appearing.  This  is  the  negative 
consecutive  sensation.  In  the  third  experiment  we 
take  two  cards,  one  red  and  the  other  green,  and 
place  them  on  a  table,  one  a  short  distance  before 
the  other;  then,  with  a  sheet  of  glass  held  before 
the  eye,  we  look  at  one  of  the  cards  through  the 
transparency  and  at  the  same  time  try  to  obtain  the 
reflected  image  of  the  other  card  in  order  to  carry  it 
on  to  the  first;  as  soon  as  the  images  of  the  two 
cards  are  superposed,  their  colours  blend,  and  we 
obtain  a  resultant  colour  which  is  generally  grayish 
(the  exact  tint  depends  upon  the  colour  of  the  cards, 

*\Vithout  wishing  to  raise  any  complicated  physiological  problems  here, 
we  may  recall  the  fact  that  a  general  agreement  does  not  exist  upon  the  ex- 
planation of  simultaneous  contrast  and  consecutive  images.  Helmholtz 
attributes  the  effects  of  the  simultaneous  contrast  to  an  error  of  judgment;  as 
for  consecutive  sensations,  he  localizes  them  in  the  retina,  and  explains  them 
by  Young's  theory  and  that  of  Fechner.  For  our  part,  we  entirely  share  Dr. 
Parinaucf's  opinion,  which  assigns  a  cerebral  seat  to  those  two  phenomena, 
and  attributes  to  them  as  their  sole  cause  a  material  modification  of  the 
nervous  centres.  (Soc.  de  Bioi.,  May  13  and  July  22,  1882). 


40  THE  PSYCHOLOGY  OF  REASONING. 

the  intensity  of  the  light,  etc.).  This  is  the  blend- 
ing of  complementary  colours. 

We  may  repeat  these  three  experiments  with 
cards  coloured  by  suggestion,  that  is  to  say  with 
hallucinations  of  colour.  If,  as  M.  Parinaud  has 
shown,  we  produce  in  a  patient  the  hallucination 
of  red  on  one-half  of  the  white  sheet,  she  sees  green 
appearing  on  the  other  half.  If,  as  we  have  ob- 
served along  with  Dr.  Fere,  we  make  a  red  cross 
appear  on  a  white  sheet,  the  patient,  after  having 
contemplated  this  imaginary  cross  for  several  mo- 
ments, sees  upon  another  sheet  of  paper  a  green 
cross.  Finally,  if  we  teach  her  to  superpose, 
according  to  the  process  described,  cards  coloured 
green  and  red  by  suggestion,  the  patient  sees 
the  resultant  gray  tint,  which  is  produced  by  the 
blending  of  these  two  complementary  colours. 

In  view  of  these  results,  is  it  possible  to  doubt 
that  visual  hallucination  results  from  an  excitation 
of  the  sensory  centre  of  vision?  If  it  were  other- 
wise, how  could  we  understand  that  hallucination 
should  give  rise  to  the  same  chromatic  effects  as 
sensation? 

We  may  transfer  all  these  phenomena  revealed 
by  the  study  of  visual  hallucination  to  the  visual 
image  itself.  This  extension  of  experience  is  so 
much  the  more  legitimate  since  Wundt  has  shown 
that  the  simple  image  of  a  colour,  contemplated  for 
a  long  time  in  the  imagination,  gives  rise  to  the 
consecutive  sensation  of  a  complementary  colour. 
If  we,  in  our  minds,  gaze  fixedly  for  some  moments 
at  the  image  of  red,  we  perceive,  on  opening  our 


IMAGES.  41 

eyes  upon  a  white  surface,  a  green  tint.*  It  is 
difficult  to  repeat  this  experiment,  for  it  demands 
a  power  of  visualization  which  everybody  does  not 
possess.  To  take  myself  as  an  example,  I  cannot 
imagine  a  colour  clearly ;  I  am  a  visuel  of  a  very 
mediocre  type.  Therefore  it  is  not  astonishing 
that  I  fail  to  obtain  a  consecutive  coloured  sensation. 
But  my  excellent  friend,  Dr.  Fere,  easily  succeeds  in 
doing  this.  He  can  imagine  a  red  cross  so  vividly 
as  to  see  afterwards,  on  a  sheet  of  paper,  a  green 
cross;  thus  he  sees  not  only  the  colour,  but  the 
form.f 

These  facts  show  the  strict  analogy  existing  be- 
tween the  sensation,  the  hallucination  and  the 
image;  we  may  conclude  from  this  that  whether 
we  have  the  sensation  of  red,  whether  we  have  the 
recollection  of  red,  or  whether  we  see  red  in  a  hal- 
lucination, it  is  always  the  same  cell  which  vibrates.:}: 

So  far  we  have  been  content  to  assert  that  the 
image  has  the  same  seat  as  the  sensation,  without 
seeking  to  determine  anatomically  what  that  seat 
is.  The  preceding  experiments  do  not  enable  us  to 
solve  this  last  question,  which  is  much  more  com- 
plicated and  difficult  than  the  first.  We  might  here 
introduce  the  principal  results  of  the  study  of  cereb- 
ral localization,  which  seem  to  show  that  the  sen- 
sory centres  are  situated  at  the  level  of  the  cerebral 
surface-layers,  in  a  zone  still  ill-defined,  probably 

*Cited  by  Bain  in  the  Appendix  to  The  Senses  and  the  Intellect. 

tThis  experiment  affords  an  objective  sign  which  allows  us  to  recognize 
whether  a  person  belongs  to  the  visual  type. 

JA11  the  preceding  experiments  have  treated  of  the  visual  image.  The 
reader  will  judge  to  what  extent  it  is  legitimate  to  extend  the  conclusion 
derived  from  them  to  the  images  of  the  other  senses. 


42  THE  PSYCHOLOGY  OF  REASONING. 

situated  behind  the  motor  zone.  But  we  prefer  to 
confine  ourselves  to  the  basis  of  hypnotic  experi- 
mentation, from  which  we  may  still  learn  some- 
thing upon  this  subject.  It  is  a  primary  fact  in 
the  study  of  hypnotic  hallucinations  that  these 
sensory  troubles,  when  they  have  a  unilateral  form, 
are  transferable  by  the  magnet.*  This  transfer  is 
accompanied  by  a  certain  number  of  objective  signs 
which  exclude  all  idea  of  simulation;  thus  the 
shifting  of  the  phenomenon  is  followed,  in  certain 
subjects,  by  a  shifting  in  the  inverse  direction,  then 
by  several  other  shiftings,  phenomena  which  have 
been  described  in  connection  with  the  transfer  of 
anaesthesia  by  the  name  of  consecutive  oscillations; 
further,  according  as  the  transfer  is  effected,  the 
patient  complains  of  pains  in  the  head,  which  oscil- 
late from  one  side  of  the  head  to  the  other;  these 
characteristic  pains,  which  we  have  proposed  to  call 
transfer  pains,  are  not  diffuse;  they  have  a  fixed 
seat,  and  that  a  most  remarkable  one.  In  the  case 
of  hallucinations  of  the  sight,  the  pain  in  the  head 
corresponds  to  the  anterior  part  of  the  inferior 
parietal  lobule,  as  M.  Fern's  researchesf  in  cranio- 
cerebral  topography  have  enabled  us  to  ascertain ; 
in  the  case  of  auditory  hallucinations,  the  painful 
spot  corresponds  to  the  anterior  part  of  the  sphe- 
noidal  lobe.  These  two  localizations  are  in  perfect 
agreement  with  the  results  of  clinico-anatomical 
reseaches;  they  therefore  deserve  to  be  taken  into 

*Binet  and  Fere,  Le  transfert  psyschique  (Revue  philosophique, 
January,  1885). 

tCh.  Fer6,  Note  sur  quelques  points  de  la  topographic  du  cerveau 
(Arch,  de  phys.  norm,  et  path..  1876,  p.  247);  Nouvelles  Kecherches  sur  la 
topographic  crania-cerebral  (Revue  d'anthrop.,  1881.  p.  468), 


IMAGES.  43 

serious  consideration.  The  centre  of  visual  sensa- 
tions has  been  placed  in  the  inferior  parietal  lobule, 
and  the  auditory  centre  in  the  sphenoidal  lobe.  It 
therefore  seems  permissible  to  consider  that  visual 
images  and  auditory  images  very  probably  result 
from  the  excitation  of  these  two  centres. 

We  finally  reach  the  same  conclusion  as  Herbert 
Spencer  and  Bain,  but  with  the  advantage  of  pred- 
icating proofs  at  our  disposal  for  what  these 
authors  considered  as  merely  probable:  "The 
renewed  feeling, ' '  said  Bain,  ' '  occupies  the  very  same 
parts  and  in  the  same  manner  as  the  original  feel- 
ing." 

III. 

We  have  not  yet  finished  our  short  study  of 
Images.  After  having  determined  their  seat  in  the 
brain,  we  shall  proceed  to  indicate  their  principal 
physiological  properties. 

Mr.  Spencer  calls  images  faint  states,  in  oppo- 
sition to  sensations,  which  are  vivid  states.  The 
term  is  correct.  The  lack  of  vividness  of  images  is 
one  of  the  reasons  which  prevent  them  from  being 
conveniently  observed  and  which  explains  why  their 
nature  has  so  long  been  unrecognized.  In  order 
to  study  them  it  is  necessary  to  compare  them  with 
consecutive  images  of  sight,  phenomena  which  follow 
the  impression  of  an  exterior  object  on  the  retina. 

We  know  that  consecutive  images  are  of  two 
kinds,  positive  and  negative.  Place  a  small  red 
square  upon  a  brightly  lighted  white  surface ;  look 
at  this  square  for  a  second,  then  shut  your  eyes 


44     THE  PSTCHOLOGT  OF  REASONING. 

without  strain,  by  covering  them  with  your  hand, 
and  you  see  the  red  square  appearing;  this  is  the 
positive  image.  Repeat  the  same  experiment  by 
gazing  for  a  long  time  at  the  red  square,  then,  on 
closing  the  eyes  or  fixing  them  on  a  different  point 
on  the  white  surface,  you  will  see  this  same  square 
appearing,  but  instead  of  being  red  it  will  be  green, 
the  complementary  tint ;  this  is  the  negative  image. 

The  consecutive  image  constitutes  a  transition 
type  between  the  sensation  and  the  ordinary  image ; 
it  is  like  the  sensation  inasmuch  as  it  immediately 
follows  the  action  of  a  ray  of  light  upon  the  retina, 
and  it  is  like  the  image  inasmuch  as  it  survives  that 
action.  The  consecutive  image  is  generally  fairly 
intense ;  it  may  be  experimented  upon  with  more 
result  than  the  ordinary  image. 

M.  Parinaud  has  demonstrated  the  cerebral  seat 
of  the  consecutive  image  by  the  following  experi- 
ment (Soc.  de  BioL,  I3th  May,  1882): 

"M.  Beclard  relates  as  follows,  in  his  treatise  on 
physiology,  an  experiment  which  is  little  known : 
'The  impression  of  a  colour  upon  the  retina  awakens 
on  the  same  point  on  the  other  retina  the  impres- 
sion of  the  complementary  colour.  Example :  Shut 
one  eye,  gaze  for  a  long  time  with  the  open  eye  at 
a  red  circle ;  then  shut  this  eye,  open  the  one  which 
was  shut,  and  you  will  see  a  green  aureole  appear- 
ing/ (Edition  dated  1866,  p.  863.) 

"Thus  presented,  this  experiment  is  open  to  criti- 
cism; its  very  formula  enunciates  an  error;  but,  re- 
stored to  its  true  meaning,  it  contains  the  demonstra- 
tion of  the  proposition  which  I  have  just  put  forward. 


IMAGES.  45 

"In  order  to  give  a  proper  account  of  the  nature 
of  the  sensation  developed  in  the  eye  which  has  not 
received  the  impression,  let  us  first  of  all  see  what 
takes  place  in  the  eye  which  receives  the  impres- 
sion. 

"Shutting  the  left  eye,  for  the  moment  excluded 
from  the  experiment,  we  gaze  at  a  red  circle  on  a 
sheet  of  white  paper,  or  better,  at  a  point  marked 
at  the  centre  of  the  circle,  in  order  to  fix  the  eye 
better.  After  some  seconds  the  white  background 
loses  its  intensity  and  the  colour  itself  becomes  dim. 
Drawing  the  circle  away  without  taking  our  gaze 
off  the  point,  we  see  appearing  on  the  paper  the 
image  of  the  circle  coloured  green  and  brighter  than 
the  background;  this  is  the  negative  image.  Shut 
the  eye,  and  the  image,  after  having  disappeared 
for  an  instant,  is  reproduced  with  the  same  charac- 
teristics. 

"Let  us  now  repeat  Beclard's  experiment — that 
is  to  say,  at  the  moment  when  we  draw  away  the 
circle,  let  us  shut  the  impressed  right  eye  and  open 
the  left  eye,  gazing  always  at  the  paper. 

"The  image  of  the  circle  does  not  appear  im- 
mediately. 

"The  white  of  the  background  darkens  at  first, 
and  it  is  only  then  that  the  image  takes  form,  col- 
oured in  green  and  brighter  than  the  background. 
It  is  the  same  negative  image,  exteriorized  by  the 
left  eye,  as  we  recognized  in  the  right  eye  which 
received  the  impression.* 

*M.  Giraud-Teulon,  who  has  repeated  the  experiment,  attributes  the 
same  characters  to  it  (Unpublished  note  sent  to  M.  Charcot). 


46 


THE  PSYCHOLOGY  OF  REASONING. 


"We  may  produce  the  same  transfer  with  the 
positive  image  by  varying  the  conditions  of  the 
experiment. 

"The  exteriorization  of  the  adventitious  image 
by  the  eye  which  has  not  received  the  impression 
necessarily  implies  the  intervention  of  the  brain 
and,  in  all  probability,  the  cerebral  seat  of  the 
image  itself."* 

This  experiment  on  the  consecutive  image  seems 
to  me  to  be  very  important  for  our  theory ;  I  have 
repeated  it  a  very  large  number  of  times.  In  the 
course  of  these  studies  I  have  noticed  some  curious 
phenomena.  First  of  all,  the  experiment  may  be 
made  with  both  eyes  open.  We  gaze  at  a  red  cross 
with  the  right  eye,  keeping  the  left  eye  open,  but 
preventing  this  eye  from  seeing  the  cross  by  inter- 
posing a  screen.  At  the  end  of  some  seconds  we 
shut  the  right  eye;  and  shortly  after  the  left  eye, 

*M.  Parinaud  adduces  a  second  proof,  which  seems  to  us  much  less  satis- 
factory. He  remarks  that  the  consecutive  image  follows  the  intentional 
movements  of  the  eye,  but  is  not  displaced  when  the  optical  axis  is  deviated 
by  the  finger.  Now,  a  retinal  image,  he  says,  would  be  displaced  in  the 
mechanical  deviation  of  the  ball,  as  well  as  hi  its  intentional  movements. 
The  conclusion  does  not  seem  to  us  to  be  just.  It  is  readily  admitted  in 
psychology  that  we  perceive  the  movements  of  bodies  by  the  eye  in  two  ways: 
ist,  when  the  eye  is  steady  and  the  image  of  the  object  changes  its  place  on 
the  retina;  2nd.,  when  the  eye  is  in  movement  and  the  image  of  the  object 
does  not  change  its  place  on  the  retina.  This  last  case  is  that  in  which  we 
follow  a  moving  object  with  our  eyes,  for  example  a  rocket  rising  in  the  air. 
It  has  moreover  been  remarked  that  the  state  of  repose  or  movement  of  the 
eye  translates  itself  into  consciousness  by  the  absence  or  the  presence  of  the 
sensations  which  accompany  the  contractions  of  the  ocular  muscles;  that  is 
that  our  consciousness  takes  account  solely  of  intentional  movements.  These 
two  rules  explain  the  majority  of  optical  illusions  relating  to  movement. 
Thus  the  consecutive  images  appear  to  move  with  the  gaze,  for  in  this  case 
we  experience  muscular  sensations  which  are  the  sign  of  the  movement  of  the 
eye,  and,  in  addition,  the  consecutive  image  is  not  displaced  on  the  retina. 
When  the  eye  is  mechanically  deviated,  we  have  no  muscular  sensations,  the 
eye  seems  steady;  consequently,  on  the  one  hand  the  exterior  objects,  which 
are  really  steady,  appear  to  move,  for  their  image  is  displaced  on  our  retina, 
considered  as  fixed,  and  on  the  other  hand  the  consecutive  images  appear 
steady,  for  their  image  does  not  change  its  place  at  all  on  our  retina,  con- 
sidered as  fixed.  In  short,  every  object  which  appears  to  move  with  the 
movements  of  the  eye  ought  to  appear  steady  when  the  eye  is  mechanically 
deviated,  and  vice  versa.  These  are  the  results  of  our  psychical  education. 
No  argument,  either  for  or  against  the  retinal  seat  of  the  consecutive  image 
can  be  drawn  therefrom. 


IMAGES.  47 

which  has  remained  constantly  open,  sees  the  point 
on  the  paper  at  which  it  gazes  become  covered  with 
a  faint  shadow,  and  at  the  middle  of  this  darkened 
surface  appears  a  green  cross. 

We  must  also  note  the  changes  which  take  place 
when  seeing  the  transferred  consecutive  image;  it 
appears,  as  M.  Parinaud  has  very  fitly  remarked, 
after  a  certain  delay;  it  never  lasts  very  long,  at 
least  with  my  eyes ;  it  usually  disappears  at  the  end 
of  two  seconds,  and  the  paper  resumes  its  original 
white  tint  at  the  same  time.  But  this  is  not  all, 
and  if  we  keep  our  eye  fixed  on  the  same  point  we 
see  the  paper,  some  seconds  after,  darken  once 
more  and  the  image  reappear  with  the  same  charac- 
teristics of  form  and  colour  as  it  had  at  first.  The 
number  of  these  oscillations  seems  to  depend  on  the 
intensity  of  the  image;  I  have  often  counted  three 
of  them. 

I  have  also  found  that  the  other  eye,  the  one 
which  has  gazed  steadily  at  the  red  cross,  preserves 
its  consecutive  image  during  all  this  time,  and  that 
we  can,  by  opening  and  shutting  our  two  eyes 
alternately,  see  the  direct  consecutive  image  and 
the  transferred  consecutive  image  succeed  each 
other. 

This  succession  of  the  two  images  allows  us  to 
compare  them.  They  do  not  always  have  the  same 
characteristics;  I  have  found  that  there  is  a  fairly 
decided  difference  of  tint  for  certain  colours.  For 
example,  an  orange-coloured  wafer  gives  me  a  con- 
secutive image  which  is  almost  blue  when  seen 
directly,  and  almost  green  when  it  is  transferred ; 


48  THE   PSTCHOLOGT  OF  REASONING. 

B 

this  difference  is  maintained  no  matter  which  eye  is 
used  at  the  beginning  of  the  experiment.  The  two 
images  present  practically  the  same  tint  for  other 
colours. 

Another  proof  of  the  cerebral  seat  of  the  con- 
secutive image  is  that  it  sometimes  appears  long 
after  the  impression  and  in  this  case  it  resembles  an 
ordinary  recollection.  Newton,  by  an  effort  of 
attention,  was  able  to  reproduce  a  consecutive 
image,  produced  by  gazing  steadily  at  the  sun  sev- 
eral weeks  previously.  It  is  well  known,  says  M. 
Baillarger,  that  persons  who  are  in  the  habit  of 
using  the  microscope  sometimes  find  objects  which 
they  have  been  examining  for  a  long  time  reappear 
spontaneously  some  hours  after  they  have  left  their 
work.  M.  Baillarger,*  having  worked  some  hours 
daily  for  several  days  at  preparing  specimens  of 
brains  with  fine  gauze,  saw  all  at  once  gauze  contin- 
ually covering  the  objects  in  front  of  him, 
and  this  hallucination  was  repeated  for  some  days. 
This  is  an  analogous  case  to  that  of  M.  Pouchet, 
who  saw  (Socidtd  de  Biologie,  2Qth  April,  1882), 
while  walking  in  Paris,  the  images  of  his  microscopic 
preparations  superposing  themselves  on  exterior 
objects.  This  phenomenon  is  not  rare;  numerous 
examples  are  to  be  found  for  the  seeking.  This 
reviviscence  of  the  long-expired  consecutive  image, 
a  long  time  after  the  excitative  sensation  has  ceased 
to  act,  completely  excludes  the  idea  that  the  con- 
secutive image  is  preserved  in  the  retina;  the  preser- 
vation is  made  in  the  brain,  and,  very  probably, 

*Quoted  by  Taine,  On  Intelligence,  p.  53. 


IMAGES.  49 

when  the  image  reappears,  it  does  not  involve  the 
cones  and  rods  of  the  retina  in  fresh  activity. 

We  may  therefore  admit,  as  a  very  probable  fact, 
that  the  consecutive  image  has  a  cerebral  seat. 
This  conclusion  is  interesting  for  the  psychologist; 
because  it  leads  him  to  establish  a  parallel  between 
the  consecutive  image  and  the  image  of  memory. 
In  what  do  they  differ?  First  of  all,  in  intensity; 
the  consecutive  image  is  so  vivid  that  it  may  be 
projected  upon  a  screen  and  fixed  there  by  draw- 
ing. Are  there  many  recollections  which  could  be 
exteriorized  in  the  same  fashion?  Then,  by  the 
mode  of  appearance;  most  frequently  the  consecu- 
tive image  immediately  follows  a  visual  sensation, 
sometimes  it  appears  spontaneously  much  later,  and 
it  is  never  excited  by  a  psychical  cause,  by  associa- 
tion of  ideas,  as  are  the  ordinary  images  of  memory. 
Observers  have  been  struck  with  this  fact.  M. 
Pouchet  has  remarked  that  at  the  moment  when 
the  image  of  his  microscopic  preparations  rose  be- 
fore his  eyes,  he  was  in  a  cab,  chatting  with  a  per- 
son who  knew  nothing  of  science,  and  he  has  been 
unable  to  perceive  the  slightest  connection  between 
this  image  and  the  subject  of  his  conversation. 

The  comparison  of  the  consecutive  image  with 
the  image  of  memory  is  of  considerable  interest ;  for 
experiment  shows  that  the  consecutive  image  pos- 
sesses a  certain  number  of  attributes,  which  further 
belong  also  to  the  image  of  memory.  Thus:  First, 
it  changes  its  place  with  intentional  movements  of 
the  eye  and  movements  of  the  head  when  the  look 
is  fixed;  second,  it  becomes  larger  when  the  screen 


50  THE  PSrCHOLOGT  OF  REASONING. 

on  which  it  is  projected  is  drawn  away,  and  shrinks 
when  the  screen  is  brought  nearer;  third,  it  is  dis- 
torted with  the  inclination  of  the  screen  and  it 
lengthens  in  the  direction  of  the  inclination. 

A  real  image,  painted  on  the  screen,  behaves 
quite  otherwise.  If  the  screen  be  drawn  away 
from  the  eye,  this  image  becomes  smaller;  if  the 
screen  be  brought  nearer,  the  image  becomes  larger ; 
if  the  screen  be  inclined,  the  image  is  distorted  and 
shrinks  in  the  direction  of  the  inclination.  This 
is  what  painters  call  foreshortening*  In  short,  the 
consecutive  image  and  the  real  image  (the  sensa- 
tion) present  inverse  properties  up  to  a  certain 
point.  What  is  the  reason  of  this?  The  question 
may  be  readily  answered. 

Let  us  first  of  all  suppose,  for  greater  clearness, 
that  the  consecutive  image  has  its  seat  in  the  retina, 
with  the  reservation  of  modifying  our  demonstration 
afterwards  to  make  it  agree  with  the  theory  of  the 
cerebral  seat.  We  must  depart  from  the  principle, 
so  firmly  established  by  Helmholtz,  that  every  sub- 
jective sensation  is  perceived,  exteriorized  and 
localized  in  the  same  fashion  as  if  it  corresponded 
to  an  exterior  object.  Let  the  consecutive  image 
be  A'  B',  on  the  retina;  if  it  be  projected  outside, 
on  a  screen  held  at  E  F,  it  will  have  the  dimension 
of  the  line  A  B,  because  that  would  be  the  dimen- 
sion of  an  object  which,  placed  at  the  distance  of 
the  screen,  would  make  on  the  retina  an  image 

*It  is  only  after  a  little  exercise  that  one  can  succeed  in  giving  an 
account  of  these  changes  in  the  dimensions  of  the  image,  because,  as  they  do 
not  correspond  to  any  change  in  real  dimensions,  we  have  contracted  the 
habit  of  correcting  them. 


IMAGES. 


51 


equal  to  A'  B' ;  in  fact,  the  two  lines  A'  C  and  B' 
C  are  carried  from  the  two  extremities  of  the  image 
to  the  optical  centre  of  the  eye  and  produced  until 
they  meet  the  line  A  B.  Now  let  us  alter  the  dis- 
tance of  the  screen,  and  what  happens?  As  the 
subjective  image  is  of  constant  size  on  the  retina,  it 
must  assume  on  the  screen  the  dimension  of  an 
object  which,  situated  at  the  new  distance  where 
the  screen  is  placed,  would  make  on  the  retina  an 
image  equal  to  A'  B'.  Therefore  we  have  only  to 
calculate  the  successive  sizes  of  an  object  subject  to 
this  condition  of  always  producing  at  the  back  of 
the  eye  a  retinal  image  of  the  same  size,  in  spite  of 
its  changes  of  distance. 

In  order  to  simplify  the  problem,  we  shall  give 
the  consecutive  image  the  form  of  a  circle;  there- 
fore, we  may  replace  the  visual  angle  A  C  B  by  a 
right  circular  cone,  with  its  vertex  at  C,  and  A  C 
and  B  C  as  its  generating  lines.  This  granted, 
when  the  consecutive  image  is  projected  on  a  screen, 


the  screen  cuts  this  cone,  and  the  size  and  form  of 
the  conic  section  are  those  of  the  object  which,  at 
the  distance  at  which  the  screen  is  held,  produces 
a  retinal  image  equal  to  A'  B'  ;  consequently  they 


52     THE  PSTCHOLOGT  OF  REASONING. 

are  also  those  of  the  projected  consecutive  image. 
Thus,  when  the  screen  is  held  vertically  (that  is  to 
say,  perpendicular  to  the  optical  axis),  the  consecu- 
tive image  must  have  a  circular  form,  because  the 
section  is  made  in  a  plane  perpendicular  to  the  axis 
of  the  cone  and  is  of  circular  form ;  when  the  screen 
is  inclined,  the  consecutive  image  must  lengthen, 
because  the  section  is  oblique  and  of  elliptical  form ; 
when  the  screen  is  drawn  away,  the  image  must 
become  larger,  because  the  section  is  made  further 
from  the  vertex  of  the  cone  and  becomes  larger. 
This  is  confirmed  by  experiment. 

That  this  is  not  so  for  the  real  image,  painted 
upon  the  screen,  is  because  its  apparent  diameter 
augments  when  the  object  is  brought  nearer,  dimin- 
ishes when  it  is  drawn  away,  and  diminishes  in  the 
direction  of  the  inclination  when  it  is  inclined. 
We  shall  not  dwell  upon  this  point. 

One  may  perhaps  be  tempted  to  conclude  from 
this  demonstration  that  the  consecutive  image 
really  has  its  seat  in  the  retina,  for  it  would  not 
behave  otherwise  if  it  were  retinal.  But  it  is  to  be 
remarked  that  the  transferred  consecutive  image 
possesses  the  same  properties.  We  have  several 
times  stated  that  it  enlarges  and  contracts  when 
the  screen  is  drawn  away  and  brought  nearer. 
Will  it  be  maintained  that  this  transferred  image  is 
retinal?  Received  by  the  right  eye,  it  is  exterior- 
ized by  the  left  eye,  which  has  remained  closed 
until  the  last  moment ;  it  is  therefore  very  probable 
that  it  has  not  impressed  the  left  retina. 

"It  is  rational   to  admit,"    says   M.  Richer  on 


IMAGES.  53 

this  subject,  "that  the  retina  has  an  exact  represen- 
tation of  itself  in  the  cerebral  visual  centre.  There 
exists  a  sort  of  cerebral  retina  each  point  of  which  is 
in  intimate  connection  with  corresponding  points 
of  the  peripheral  retina."*  Therefore  it  is  under- 
stood that  an  impression  conveyed  directly  to  a 
point  of  this  cerebral  retina  (the  consecutive  image) 
produces  the  same  effect  on  consciousness  as  an  im- 
pression which  would  lie  on  the  corresponding  point 
of  the  peripheral  retina,  to  right  or  to  left,  either 
above  or  below,  or  on  the  yellow  spot. 

We  willingly  admit,  until  we  have  proof  to  the 
contrary,  that  the  properties  of  the  consecutive 
image  are  common  to  the  ordinary  image,  to  recol- 
lection for  example,  although  they  could  not  be 
observed  in  an  image  so  feeble.  But  there  are 
cases  where  the  image,  evoked  by  a  person  of 
healthy  mind,  attains  a  degree  of  intensity  suffi- 
cient to  exteriorize  it.  Brierre  de  Boismont,  who 
endeavoured  to  impress  upon  his  mind  the  figure  of 
one  of  his  friends,  a  clergyman,  had  acquired  the 
faculty  of  evoking  it  whether  his  eyes  were  open 
or  shut ;  the  image  appeared  to  him  to  be  exterior, 
situated  in  the  direction  of  the  line  of  sight;  it  was 
coloured,  its  outlines  were  fixed  and  endowed  with 
all  the  characteristics  belonging  to  the  real  person. 
We  earnestly  invite  those  who  possess  the  gift  of 
visualizing  to  try  the  following  experiment :  Think 
of  a  red  cross,  project  it  on  a  screen  and  see  if  it 
behaves  like  a  consecutive  image,  if  it  enlarges 
when  the  screen  is  brought  nearer  and  contracts 

*Etudes  cliniques  sur  I  ''hystero-epilepsic^  2nd  edition,  1885,  p.  714. 


54  THE   PSYCHOLOGY  OF  REASONING. 

when  it  is  drawn  away.  The  success  of  this  experi- 
ment would  give  a  decisive  confirmation  to  our 
thesis. 

Such  are  the  positive  characteristics  of  consecu- 
tive images,  and  probably  of  all  images.  They 
have  also  a  certain  number  of  equally  important 
negative  characteristics,  which  serve,  as  much  and 
more  than  the  first,  to  distinguish  them  from  sensa- 
tions. 

We  know  that  our  sensations  are  directly  modi- 
fied in  consequence  of  the  movements  which  we 
make;  the  aspect  of  my  home  is  modified  when  I 
shut  or  when  I  open  my  eyes,  when  I  come  nearer 
it  or  go  further  away,  when  I  press  my  eyes  so  as 
to  see  double,  or  when  I  interpose  a  prism  so  as  to 
see  it  deviated,  or  when  I  reflect  it  in  a  mirror  so  as 
to  have  a  symmetrical  figure  of  it,  or  when  I  look 
at  it  through  an  opera-glass  so  as  to  have  an  en- 
larged view  of  it.  ...  It  is  clear  that  none  of 
these  experiments  has  any  influence  on  a  mental 
image.  When  I  think  of  .an  absent  friend,  and  the 
visual  image  of  his  countenance  is  about  to  rise  in 
answer  to  my  thought,  I  might  try  in  vain  to 
modify  the  perspective  of  this  image  by  changing 
my  position,  or  to  double  it  by  pressing  my  eye. 
The  attempt  equally  fails  in  the  case  of  the  con- 
secutive image.  M.  Parinaud  has  made  an  experi- 
ment in  order  to  show  conclusively  that  a  consecu- 
tive image  cannot  be  deviated  by  looking  at  it 
through  a  prism.  We  select  the  following  passage 
from  a  manuscript  note  which  he  has  been  good 
enough  to  send  us: 


55 

"Gaze  steadily,"  he  says,  "with  one  eye  at  a 
thin  strip  of  red  paper  on  a  white  background;  after 
a  minute,  slip  between  the  strip  and  the  eye  a  prism 
with  1 5  degrees  of  an  angle  at  its  larger  base,  keep- 
ing the  gaze  fixed,  without  trying  to  follow  the  dis- 
placement of  the  strip.  You  then  see  the  green 
consecutive  image  detach  itself  from  the  upper  part 
of  the  red  strip.  In  order  to  make  sure  that  it  is 
only  the  image  of  the  paper  that  is  displaced,  and 
that  the  consecutive  image  has  not  undergone  devi- 
ation in  the  inverse  direction,  recommence  the 
experiment  by  covering  only  a  part  of  the  red  strip 
with  the  prism ;  the  consecutive  image,  if  the  eye 
does  not  change  its  place,  protracts  exactly  that 
part  of  the  strip  which  has  not  undergone  the 
prismatic  refraction." 

To  sum  up,  sensations  and  images  form  two 
groups  of  phenomena  which  are  distinguished  by 
definite  characteristics,  positive  and  negative 
equally. 


CHAPTER  III. 

REASONING    IN    PERCEPTION. 


IN  external  perception  the  images  which  arise  in  us 
from  contact  with  objects  derive  a  group  of  proper- 
ties from  their  origin  which  are  entirely  wanting 
in  isolated  images,  which  we  studied  in  the  preced- 
ing chapter.  Directly  suggested  by  exterior  im- 
pressions, they  associate  themselves  organically 
with  these  impressions,  so  as  .to  form  an  indivisible 
whole  which  corresponds  to  the  idea  of  a  single 
object.  By  means  of  this  sensory  bond  each  image 
consequently  undergoes  all  the  modifications  which 
the  sensation  directly  experiences.  Practically,  as 
regards  the  observer,  it  behaves  like  a  true  sensa- 
tion. 

The  chapter  which  follows  might  therefore  be 
entitled :  ' '  The  properties  of  images  which  arc  asso- 
ciated with  sensations. ' ' 

In  the  study  of  these  phenomena  we  shall  turn 
once  more  to  hypnotic  hallucinations,  for  in  the 
normal  state  they  are  too  weak  to  be  observed. 
But  here  a  preliminary  objection  arises:  How  can 
the  hallucination  be  of  use  in  the  study  of  normal 
perception,  an  operation  which  is  produced  by  a 
cooperation  of  the  senses  and  the  mind?  Is  the 
hallucination  not  a  sort  of  delirious  conception 

56 


REASONING  IN  PERCEPTION.  57 

which  arises  wholly  from  a  diseased  brain?  When 
we  say  to  a  hypnotized  subject:  There  is  a  serpent! 
and  when,  looking  at  the  ground,  she  sees  the 
serpent  crawling  towards  her,  what  is  real,  what  is 
objective  in  this  apparition?  Such  is  the  objection 
which  may  be  made  a  priori.  But  by  carefully 
observing  the  hypnotic  hallucination  (the  only  one 
we  shall  refer  to),  and  also  by  replacing  mere 
observation  by  experiment,  we  find  that  a  part  of 
sensation  enters,  if  not  always,  at  least  often,  into 
this  phenomenon.  This  is  perhaps  not  an  absolute 
rule,  but  the  case  is  very  common. 

Here  is  a  first  experiment  which  proves  this: 
We  present  a  pure  white  sheet  of  paper  to  the  sub- 
ject and  say  to  him:  "See,  here  is  your  portrait." 
The  subject  immediately  sees  his  portrait  appearing 
on  the  white  surface,  he  describes  the  pose  and  the 
costume,  adding  to  the  suggested  hallucination 
with  his  own  imagination,  and  if  the  subject  be  a 
woman,  she  is  usually  dissatisfied,  finding  the  por- 
trait little  flattered.  One  of  them,  who  was  pretty 
enough,  but  -whose  complexion  was  covered  with 
little  freckles,  said  to  me  one  day  when  looking  at 
her  imaginary  portrait:  "I  have  a  great  many 
freckles,  but  I  have  not  so  many  of  them  as  that." 
When  the  subject  has  contemplated  the  white  card 
for  some  time,  we  take  this  card  and  shuffle  it 
amongst  a  dozen  cards  of  the  same  kind ;  there  are 
now  thirteen  similar  cards,  and  we  would  be  unable 
to  recognize  the  one  which  carried  the  hallucination 
if  we  did  not  take  care  to  mark  it  after  having 
taken  it  from  the  hands  of  the  patient.  But  the 


58     THE  PSTCHOLOGT  OF  REASONING. 

patient  has  no  need  of  marks;  if  we  offer  her  the 
bundle  of  cards,  telling  her  to  look  for  her  portrait, 
she  recognizes  the  first  card,  usually  without  mak- 
ing a  mistake;  better  still,  she  always  holds  it  out 
in  the  same  vray,  and  if  we  reverse  the  card  accord- 
ing to  its  edges,  she  sees  the  imaginary  portrait 
upside  down.  But  there  is  something  still  more 
cogent.  If  we  photograph  the  white  card  and  show 
the  photographic  proof  to  the  patient  ten  days, 
twenty  days  or  a  month  after,  she  will  still  recog- 
nize her  portrait  on  it.* 

The  most  simple  way  of  explaining  this  local- 
ization of  the  imaginary  portrait  is  to  suppose  that 
the  hallucinatory  image  is  associated — in  an  uncon- 
scious manner — with  the  visual  impression  of  the 
white  card ;  so  that  every  time  this  visual  impres- 
sion is  renewed  it  suggests  the  image  by  association. 
There  are  always  some  special  details  on  a  paper 
card,  however  white  it  may  be;  we  are  able  to  find 
them  with  a  little  attention;  the  patient  perceives 
them  instantaneously  by  means  of  her  hyperaes- 
thetic  visual  sense;  these  details  serve  her  as  the 
point  of  identification  on  which  to  project  the 
image.  They  are,  as  it  were,  the  nails  which  fix 
the  imaginary  portrait  on  the  white  surface.  This 
is  so  true  that  the  portrait  experiment  is  more 
surely  successful  when  ordinary  paper  rather  than 
Bristol  board  is  used.  In  a  general  way  the  more 
visible  the  point  of  identification,  the  more  durable 
is  the  hallucination. 

•Clearly  the  experiment  does  not  succeed  every  time,  but  one  success  is 
sufficient,  under  conditions  which  exclude  fraud,  to  give  us  the  right  to  take 
it  into  account. 


REASONING  IN  PERCEPTION.  59 

We  owe  to  M.  Londe,  the  chemist  of  the  Sal- 
petriere,  the  following  corroborative  fact:  Wit — , 
being  in  a  state  of  somnambulism,  he  shows  her  the 
engraving  of  a  photograph  representing  a  view  of 
the  Pyrenees,  with  some  asses  climbing  a  hill ;  at 
the  same  time  he  says  to  her,  "See,  this  is  your 
portrait;  you  are  quite  nude."  When  she  awoke, 
the  patient  chanced  to  perceive  the  engraving,  and 
furious  at  seeing  herself  represented  in  a  state  too 
near  that  of  nature,  she  jumped  up  and  destroyed 
it.  But  two  photographic  proofs,  which  were  care- 
fully preserved,  had  already  been  taken  from  this 
engraving.  Every  time  the  patient  sees  them  she 
stamps  with  anger,  for  there  she  always  sees  herself 
represented  as  nude.  At  the  end  of  a  year  the  hal- 
lucination still  remains. 

This  exceptionally  long  survival  of  the  hallu- 
cination is  clearly  explained  by  the  point  of  identi- 
fication theory.  In  reality  the  photograph  presents 
to  the  patient  an  immense  number  of  points  of 
identification,  which,  being  associated  with  the 
hallucinatory  image,  evoke  it  by  accumulating  their 
effects  with  an  irresistible  force.*  The  most  curious 
thing  about  this  observation  is  that  the  patient 
does  not  see  these  points  of  identification,  or  rather 
does  not  take  account  of  their  nature,  for  it  is  very 
essential  that  she  should  see  them  so  as  to  project 
her  hallucination ;  but  she  does  not  succeed  in 
recognizing  that  they  form,  by  their  union,  a  view 
of  the  Pyrenees.  It  is  useless  to  endeavour  to  lead 

*It  has  been  long  remarked  that  one  recollection  is  much  more  surely 
recalled  than  another,  when  it  has  a  larger  number  of  lines  of  association  at 
its  disposal. 


60  THE   PSYCHOLOGY   OF  REASONING. 

her  from  her  error;  her  portrait  is  all  she  sees  on 
the  photograph. 

These  few  examples  will  be  sufficient  to  show 
that  hypnotic  hallucination  may,  like  perception, 
contain  two  elements:  an  impression  of  the  senses 
and  an  exteriorized  cerebral  image.  Perception, 
said  Taine,  is  a  true  hallucination.* 

It  is  true  that  the  mode  of  formation  is  not  the 
same  in  both  cases.  The  hypnotic  hallucination  is 
formed  by  an  image  suggested  by  speech,  which  is 
associated  with  a  point  of  identification,  while  in 
perception  the  image  is  directly  suggested  by  an 
impression  of  the  senses.  But  between  these  two 
acts  lies  a  third,  which  forms  a  transition  between 
them,  the  illusion  of  the  senses.  The  hypnotic 
illusion  of  the  senses  differs  in  one  point  only  from 
the  hypnotic  hallucination,  in  that  it  consists  of  the 
transformation  of  an  exterior  object,  while  the  hal- 
lucination creates  an  entirely  imaginary  object. 
Say  to  a  subject,  while  showing  him  a  hat :  There  is 
a  cat,  or  a  bird,  or  a  house;  and  you  produce  a 
hypnotic  illusion.  Pronounce  the  same  words 
without  showing  any  object,  and  you  suggest  a  hal- 
lucination. But  the  existence  of  that  object  which 
serves  as  substratum  for  the  hypnotic  illusion  does 
not  appear  to  have  any  importance,  since  it  may  be 
transformed  in  a  hundred  ways.  The  ordinary  error 
of  the  senses,  a  trouble  so  frequent  that  everybody 
knows  it  by  experience,  takes  its  place  alongside  the 
hypnotic  error  of  the  senses.  Who  has  not  heard 
a  burglar's  step  in  the  creaking  of  a  piece  of  furni- 

fA.  Binet,  L  'Hallucination  (Revue  philosophique,  April  and  May, 
1884). 


REASONING  IN  PERCEPTION.  6 1 

ture ;  who  has  not  seen  a  human  figure  in  the  con- 
fused forms  of  a  landscape  by  night?  These  illu- 
sions are  distinguished  from  those  of  hypnotism  by 
their  mode  of  formation.  In  the  hypnotic  state  the 
image  which  transforms  the  object  is  suggested  by 
speech,  it  comes  from  within ;  in  the  normal  state 
the  false  image  is  suggested  by  a  defective  vision  of 
the  object,  it  comes  from  without.  But  apart  from 
this  difference,  the  two  are  alike.  In  short,  the 
illusion  of  the  senses  is  intimately  connected  with 
exterior  perception,  which  it  in  a  manner  counter- 
feits. Consequently  perception  and  hallucination 
are  bound  together  by  an  uninterrupted  series  of 
intermediate  states.  Thus  we  are  permitted  to 
consider  the  ordinary  illusion  of  the  senses,  the 
hypnotic  hallucination,  and  finally  the  hallucination, 
as  more  and  more  accentuated  distortions  of  per- 
ception. This  proved,  we  proceed  to  utilize  these 
facts  of  the  morbid  state  in  the  study  of  the  normal 
state. 

Brewster  was  the  first  to  observe  that  if  the  eye 
of  a  person  in  the  state  of  hallucination  be  pressed, 
the  imaginary  object  is  seen  double.  The  fact  has 
been  confirmed  by  observations  made  by  Paterson, 
Despine  and  Ball.  This  last  named  doctor  has 
reported  the  most  curious  example.  It  concerned 
a  hysterical  young  girl  who,  in  the  crises  of  natural 
somnambulism,  saw  the  Holy  Virgin  appearing  to 
her  in  a  resplendent  costume.  This  miraculous 
apparition  was  invariably  doubled  by  ocular  pres- 
sure; two  Virgins  appeared  before  her.  M.  F£r£ 
has  in  his  turn  found  that  by  operating  on  hys- 


62     THE  PSrCHOLOGT  OF  REASONING. 

tcrical  subjects  who  can  be  hypnotized  it  is  possible 
to  repeat  this  curious  experiment  as  often  as  desired. 

How  shall  this  hallucinatory  diplopia  be  ex- 
plained? It  is  clear  that  we  are  unable  to  double  a 
mental  image  directly  by  pressing  on  the  eye.  If 
I  think  of  an  absent  friend,  I  shall  never  succeed  in 
seeing  him  double  by  pressing  on  my  eye.  If, 
therefore,  the  visual  hallucination  may  be  divided 
under  these  circumstances,  that  indicates  that  it  is 
not  "altogether  image";  in  reality  it  is  associated 
with  an  impression  of  the  senses — that  is  to  say, 
with  an  exterior  point  of  departure;  the  ocular 
'pressure  doubles  this  point,  and  the  cerebral  image 
shares  this  doubling  consecutively  by  a  sort  of  re- 
bound. 

Now,  this  is  precisely  what  occurs  in  visual  per- 
ception. When  we  look  at  an  object  while  touch- 
ing or  pressing  on  our  eye  to  make  it  deviate  from 
its  normal  position,  we  see  the  object  double;  the 
object,  we  say.  Now,  what  is  an  object?  A  group 
of  sensations  and  images ;  the  images  are  therefore 
doubled,  like  the  sensations;  the  sensory  diplopia 
is  therefore  accompanied  by  a  mental  diplopia. 
But  the  fact  is  not  readily  apparent.  It  would  not 
be  noticed,  save  for  the  hallucination,  which  hyper- 
trophies it,  rendering  the  image  enormous  and 
reducing  the  sensation  to  almost  nothing.  In  this 
way  pathological  facts  instruct  us  regarding  the 
normal  state.  We  learn  here  that  in  our  percep- 
tions the  image  is  so  firmly  bound  to  the  sensation 
that  it  indirectly  undergoes  its  modification ;  it  is 
doubled  when  the  sensation  is  doubled. 


REASONING  IN  PERCEPTION.  63 

M.  Fere  has  replaced  ocular  pressure  by  a  prism. 
Placing  a  prism  before  the  eye  of  a  patient  in  the 
state  of  hallucination,  he  found  that  the  hallucina- 
tion was  doubled  as  before,  and  that,  further,  one 
of  the  images  underwent  a  deviation  whose  direc- 
tion and  value  were  according  to  the  laws  of  optics. 
It  will  be  fully  understood  that  the  experiment  was 
made  when  all  exterior  objects  whose  modifications 
might  serve  as  marks  were  removed  from  the  visual 
field  of  the  patient.  For  example,  the  patient  is 
inculcated  with  the  idea  that  a  profile  portrait  is  on 
a  neighbouring  table.  If,  without  forewarning,  a 
prism  be  interposed  before  one  of  her  eyes,  the 
patient  is  astonished  to  see  two  portraits,  and  the 
one  which  is  deviated  is  always  placed  according  to 
the  laws  of  optics.  (Ch.  Fere,  Soc.  Biol.,  2gth 
Oct.,  1 88 1.)  This  second  experiment,  like  the 
first,  instructs  us  regarding  the  history  of  our  nor- 
mal perceptions;  for  normally,  when  we  place  a 
prism  before  one  of  our  eyes,  the  objects  which  we 
see  through  the  prism  appear  to  us  deviated.  Now, 
this  deviation  of  the  objects  implies  a  deviation  of 
the  images;  the  prism,  under  certain  conditions, 
deviates  an  image.  Thus  we  find,  in  the  centre  of 
the  normal  life,  the  germ  of  this  curious  experiment 
in  hypnotism. 

We  have  ourselves  contributed  to  the  develop- 
ment of  these  studies  by  replacing  the  prism  by  a 
large  number  of  other  optical  instruments.  The 
principle  being  settled,  the  experiments  offer 
scarcely  any  interest  save  that  of  curiosity.  We 
shall  confine  ourselves  to  mentioning  a  few,  refer- 


64  THE  PSTCHOLOGT  OF  REASONING. 

ring  for  details  to  our  articles  on  hallucinations. 
If,'  while  the  patient  is  contemplating  the  suggested 
imaginary  object,  for  example  a  tree  on  which  a 
bird  is  sitting,  we  place  an  opera-glass  before  her 
eyes,  she  immediately  declares  that  the  tree  is  be- 
coming very  large  and  is  drawing  nearer.  If,  revers- 
ing the  opera-glass,  we  make  the  patient  look 
through  the  objective  glass  (the  large  end),  the  tree 
suddenly  recedes,  shrinks,  and  the  bird  becomes 
completely  invisible.  The  interest  of  this  experi- 
ment lies  in  the  remarks  with  which  the  patient,  in 
the  state  of  somnambulism,  accompanies  these 
changes  in  the  imaginary  object.  The  said  Wit — 
experiences  a  most  lively  astonishment  every  time. 
When  I  make  her  look  at  a  bird  perched  on  the 
branch  of  a  tree,  she  does  not  in  the  least  under- 
stand how  this  bird  can  be  quite  near  to  her  one 
moment  and  far  distant  the  next.  I  tell  her  sev- 
eral times  that  the  bird  changes  its  position,  that  it 
flies  nearer  and  then  goes  away.  But  she  rejects  this 
explanation  entirely,  with  the  objection  that  the 
tree  also  appears  to  occupy  different  positions.  I 
reply  that  it  is  impossible,  that  the  tree  has  its 
roots  buried  in  the  ground  and  cannot  leave  the 
place  where  it  is  planted.  Then  she  concludes  that 
her  eyes  are  out  of  order,  and  that  it  is  they  which 
change  the  apparent  distance  of  the  objects.  This 
conclusion  is  really  a  very  reasonable  one,  it  being 
stated  that  the  patient  does  not  know  that  the  eye- 
piece and  the  objective  of  an  opera-glass  are  placed 
alternately  before  her  eyes. 

It  is  important  to  notice  that  the  hallucination 


REASONING  IN  PERCEPTION.  65 

is  modified  only  when  the  opera-glass  has  been 
adjusted  to  the  sight  of  the  patient.  Why?  Be- 
cause it  is  only  then  that  the  opera-glass  modifies 
her  visual  sensation ;  it  enlarges  the  surface  of  the 
exterior  body  to  which  the  image  is  applied,  thus 
enlarging  the  image,  which  acts  like  a  drawing  on 
an  india-rubber  film. 

This  experiment,  like  the  preceding  ones,  ex- 
plains the  normal  state.  Without  dwelling  on  the 
matter,  let  us  merely  remember  that  in  approaching 
a  person  our  visual  sensations  are  gradually  modi- 
fied; at  the  same  time  the  images  produced  by 
these  sensations  are  modified  in  the  same  way.  If 
we  are  at  first  very  far  away,  we  see  a  black  spot  of 
unrecognizable  character;  then  this  spot  becomes 
an  object  longer  than  it  is  broad,  then  we  distin- 
guish a  person,  then  we  know  it  to  be  a  man,  then 
a  man  of  such  and  such  a  kind,  and  finally  we 
recognize  a  certain  man.  The  images  change  in 
proportion  as  the  sensations  are  modified  by  our 
approach ;  they  become  more  abundant,  more  defi- 
nite, and  they  finally  permit  an  act  of  individual 
recognition.  Hallucination  renders  this  phenome- 
non of  the  induction  of  sensations  into  images  very 
apparent. 

In  other  experiments  we  nave  replaced  the 
opera-glass  with  a  lens,  which  enlarges  an  imaginary 
portrait  and  at  a  certain  distance  reverses  it,  by  a 
bifracting  crystal  which  produces  a  special  and 
somewhat  complicated  doubling,  and  finally  by  a 
microscope,  which  produces  a  much  greater  enlarge- 
ment than  the  lens.  But  in  these  different  cases  it 


66  THE  PSTCHOLOGT  OF  REASONING. 

is  always  a  matter  of  the  same  phenomenon  of 
refraction,  and  when  we  know  one  of  them  we  are 
able  to  understand  them  all. 

We  shall  describe,  in  conclusion,  the  mirror  ex- 
periment. If  we  produce  a  hallucination  on  a  fixed 
point,  such  as  the  hallucination  of  a  cat  on  a  neigh- 
bouring table,  it  is  possible  to  get  this  imaginary 
object  reflected  in  a  plane  mirror,  provided  that 
this  mirror  reflects  the  point  on  the  table  where 
the  imaginary  animal  is  seated.  The  patient  conse- 
quently sees  two  cats;  both  of  them  are  imaginary, 
but  it  may  be  said  that  the  reflected  one  is  still 
more  imaginary  than  the  other.  In  fact,  if  the 
patient  is  directed  to  seize  these  animals,  she  readily 
catches  the  one  on  the  table,  but  when  she  wishes 
to  seize  the  reflected  one  her  hand  encounters  the 
front  of  the  mirror,  which  prevents  it  from  going 
further.  Moreover,  observing  things  more  closely, 
it  is  noticed  that  the  mirror  gives  a  symmetrical 
image  of  the  imaginary  object,  as  if  it  were  a  real 
object.  It  is  in  this  way  that  an  imaginary  in- 
scription on  a  sheet  of  paper  is  seen  reversed 
in  the  mirror.  All  these  results  are  explained 
by  the  existence  of  the  reflected  point  of  identifi- 
cation. 

Here  we  have  a  case  which  clearly  establishes 
the  transition  between  hallucination  and  perception. 
It  is  an  example  of  an  illusion  of  the  senses,  which 
happened  to  be  reflected  by  a  mirror.  One  of  my 
friends  has  related  to  me  that,  starting  one  night 
out  of  his  sleep,  he  saw  a  human  form  before  his 
window,  which  was  faintly  lighted ;  shortly  after,  he 


REASONING  IN  PERCEPTION.  67 

recognized  that  this  apparition  represented  the  Vir- 
gin; she  was  standing,  stretching  out  her  open 
hands,  and  from  each  finger  proceeded  a  ray  of  fire. 
At  the  side  of  the  window  there  was  a  cupboard 
with  looking-glasses;  the  Virgin  was  reflected  in  the 
looking-glass  like  a  real  object;  the  second  image 
was  absolutely  similar  to  the  first ;  the  attitude  was 
the  same,  the  open  hands  were  surrounded  by  the 
same  luminous  aureole.  My  friend,  who  is  not  in 
the  least  superstitious,  did  not  allow  himself  to  be 
deceived  by  this  apparent  miracle.  On  approaching 
the  window  he  found  that  the  illusion  arose  from  a 
white  cloth  hung  on  the  fastening.  As  was  to  be 
expected,  the  image  of  the  cloth  was  reflected  by 
the  looking-glass. 

Although  this  phenomenon  may  appear  too 
natural  to  deserve  mention,  we  mention  it  because 
it  shows  that  one  and  the  same  rule  extends  to 
hallucination,  illusion  of  the  senses  and  to  percep- 
tion. These  comparisons  are  exceptionally  instruct- 
ive in  the  study  of  perception. 

We  now  understand  that  when  we  see  a  real 
object  reflected  in  a  mirror  there  happens  some- 
thing which  is  analogous  to  the  reflection  of  a  hal- 
lucination and  of  an  illusion.  The  mirror,  consid- 
ered from  the  point  of  view  of  perception,  is  a  sort 
of  repeater;  it  repeats  the  visual  sensations  which 
the  object  produces  on  us  directly.  These  repeated 
sensations  give  rise,  as  if  they  were  direct  sensa- 
tions, to  an  interpretation,  to  the  construction  of 
an  exterior  object  by  the  mind — that  is  to  say, 
definitively,  to  a  suggestion  of  images.  We  may 


68  THE  PSTCHOLOGT  OF  REASONING. 

therefore  say  that  in  the  normal  state  a  mental 
image  is  reflected  in  a  mirror  when  it  is  connected 
with  a  sensation. 

We  refer  the  reader  who  may  desire  further 
details  regarding  these  phenomena  of  optical  hallu- 
cination to  the  monograph  on  hallucination  pre- 
pared by  us  in  collaboration  with  M.  Fer£.  The 
aim  which  we  pursue  here  is  not  to  study  hallucina- 
tion, but  to  explain  exterior  perception  by  hallu- 
cination, which  is  a  very  different  thing. 

II. 

Hypnotic  experiments  on  visual  hallucinations 
have  enabled  us  to  penetrate  in  part  into  the  mech- 
anism of  our  normal  perceptions.  The  principal 
conclusion  which  is  drawn  from  them  is  as  follows : 
When  an  exterior  object  conveys  an  impression  to 
our  senses,  the  mind  adds,  upon  its  own  initiative, 
a  certain  number  of  images  to  the  sensations  expe- 
rienced. These  images,  which  complete  the  knowl- 
edge of  the  exterior  and  present  object,  do  not 
remain  inert  and  immobile  in  the  presence  of  the 
sensations,  like  two  bodies  which  have  no  chemical 
affinity  for  each  other,  or  like  two  algebraic  quanti- 
ties which  are  simply  connected  by  the  sign  -|-.  It 
is  more  than  a  juxtaposition.  In  reality  a  combi- 
nation of  sensations  and  images  is  formed,  and 
although  these  two  elements  come  from  very  differ- 
ent sources,  since  one  is  sensory  and  the  other 
ideal,  they  unite  so  as  to  form  a  single  whole. 
This  is  proved  by  the  fact  that  every  time  the 


REASONING  IN  PERCEPTION.  69 

group  of  sensations  is  modified,  a  corresponding 
modification  in  the  group  of  images  follows.  If 
the  sensation  be  deviated  by  a  prism,  the  image  is 
deviated ;  if  the  sensation  be  enlarged  by  an  opera- 
glass,  the  image  is  enlarged;  if  the  sensation  be  du- 
plicated by  a  mirror  and  made  symmetrical,  the 
image  is  reflected  and  becomes  symmetrical.  This 
resonance  on  the  part  of  the  image  is  a  phenomenon 
which  occurs  every  day,  every  hour  and  every  instant 
in  our  sensory  perceptions — that  is  to  say,  quite  close 
at  hand.  If  we  do  not  notice  it,  it  is  because  it  is 
too  delicate,  too  slight.  To  render  it  more  appar- 
ent we  must  have  recourse  to  the  hallucination, 
which  magnifies  it. 

In  common  with  many  authors,  we  shall  apply 
the  name  percept  to  the  product  of  perception — 
that  is  to  say,  the  images  of  the  exterior  object 
which  are  definitely  due  to  and  bound  to  the  excita- 
tive sensation. 

We  have  yet  to  study  the  bond  which  unites  the 
sensation  to  the  image.  The  preceding  experi- 
ments have  proved  its  existence  without  making  its 
nature  known. 

We  may  consider  external  perception  as  a  syn- 
thetic operation,  since  it  results  in  the  uniting  of 
the  information  actually  furnished  by  the  senses  to 
the  information  furnished  by  preceding  experiences. 
Perception  is  a  combination  of  the  present  with  the 
past.  To  perceive  a  body  which  is  actually  in  the 
field  of  vision,  to  recognize  in  it  a  certain  form, 
size,  position  in  space,  certain  qualities,  etc.,  is  to 
unite  in  a  single  act  of  consciousness  actual  elements 


70     THE  PSrCHOLOGT  OF  REASONING. 

—that  is  to  say,  the  optical  sensations  of  the  eye— 
and  past  elements — that  is  to  say,  a  crowd  of 
images;  it  is  to  make  a  single  body  out  of  these 
unconnected  elements.  This  is  a  phenomenon 
which  completely  escapes  consciousness;  by  con- 
sulting that  witness  alone,  the  operation  of  perceiv- 
ing an  object  appears  to  be  an  easy  and  natural  act 
which  demands  no  effort  of  reflection  on  our  part ; 
that  is  in  reality  an  illusion.  Experiment  and 
reasoning  prove  to  us  that  in  all  perception  there  is 
work. 

But  the  amount  of  work  is  not  constant;  it  is 
clear  that  it  varies  according  to  circumstances.  It 
would  be  wrong  to  think  that  there  is  only  a  single 
kind  of  perception.  Perception  is  a  form  of  activity 
which  has  a  very  variable  nature,  for  by  one  of  its 
extreme  limits  it  encloses  conscious  reasoning,  com- 
posed of  three  verbal  propositions,  and  at  the  other 
end  it  becomes  identified  with  the  most  elementary 
and  automatic  acts,  such  as  reflexes.  The  amount 
of  work  expended  in  perception  increases  in  an 
ascending  series  and  even  becomes  very  consider- 
able when  we  approach  reasonings  in  which  a  sen- 
sible amount  of  reflexion  and  comparison  occurs; 
inversely,  the  work  decreases  when  we  descend 
towards  reflex  actions,  without,  however,  vanish- 
ing altogether.  It  is  therefore  important  to  give 
some  examples  of  the  different  kinds  of  perception. 
Let  us  begin  with  the  lowest  forms. 

"First  of  all,"*  says  Mr.  Sully,  in  describing 
the  degrees  of  visual  perception,  "comes  the  con- 

*James  Sully,  Illusions,  p.  23. 


REASONING  IN  PERCEPTION.  71 

struction  of  a  material  object  of  a  particular  figure 
and  size,  and  at  a  particular  distance — that  is  to 
say,  the  recognition  of  a  tangible  thing  having 
certain  'simple  space-properties,  and  holding  a 
certain  relation  to  other  objects,  and  more  especially 
our  own  body,  in  space.  This  is  the  bare  percep- 
tion of  an  object,  which  always  takes  place  even  in 
the  case  of  perfectly  new  objects,  provided  they  are 
seen  with  any  degree  of  distinctness.  .  .  .  This 
part  of  the  process  of  filling  in,  which  is  the  most 
instantaneous,  automatic  and  unconscious,  may  be 
supposed  to  answer  to  the  most  constant  and  there- 
fore the  most  deeply  organized  connections  of  ex- 
perience. 

"The  second  step  in  this  process  of  presenta- 
tive  construction  is  the  recognition  of  an  object  as 
one  of  a  class  of  things — for  example,  oranges,  hav- 
ing certain  special  qualities,  as  a  particular  taste.  In 
this  step  the  connections  of  experience  are  less 
deeply  organized,  and  so  we  are  able  to  some  ex- 
tent, by  reflection,  to  recognize  it  as  a  kind  of  intel- 
lectual working  up  of  the  materials  supplied  us  by 
the  past. 

"A  still  less  automatic  step  in  the  process  of 
visual  recognition  is  that  of  identifying  individual 
objects,  as  Westminster  Abbey,  or  a  friend,  John 
Smith.  The  amount  of  experience  that  is  here  re- 
produced may  be  very  large,  as  in  the  case  of  recog- 
nizing a  person  with  whom  we  have  had  a  long  and 
intimate  acquaintance.  .  .  .  It  is  further  to 
be  observed  that  in  these  last  stages  of  perception 
we  approach  the  boundary  line  between  perception 


72  THE  PSYCHOLOGY  OF  REASONING. 

and  inference.  To  recognize  an  object  as  one  of  a 
class  is  often  a  matter  of  conscious  reflection  and 
judgment,  even  when  the  class  is  constituted  by 
obvious  material  qualities  which  the  senses  «may  be 
supposed  to  apprehend  immediately.  Still  more 
clearly  does  perception  pass  into  inference  when 
the  class  is  constituted  by  less  obvious  qualities, 
which  require  a  careful  and  prolonged  process  of 
recollection,  discrimination  and  comparison  for  their 
recognition.  .  .  .  To  say  where  the  line  should 
be  drawn  here  between  perception  and  observation 
on  the  one  hand,  and  inference  on  the  other,  is 
clearly  impossible." 

We  may  add  that  perception,  in  the  highest 
steps  of  its  development,  assumes  a  particular  char- 
acter. In  rudimentary  perception  the  mind  simply 
infers  from  the  sensations  which  it  receives  by  one 
of  its  organs  (for  example,  the  eye)  that  the  object 
has  yet  other  properties  which  the  other  senses 
would  perceive  if  it  were  necessary  and  if  we  wished 
it;  thus  when  we  look  at  a  red-hot  bar  of  iron,  the 
red  colour  revives  in  us  the  idea  of  heat,  which  we 
might  directly  experience  by  bringing  our  hand 
near  to  the  bar.  Such  a  perception  amounts  to  a 
substitution  of  sight  for  touch. 

But  it  is  quite  otherwise  with  the  more  complex 
perceptions  which  belong  to  reasoning  properly  so 
called.  When  we  recognize  that  a  plant  belongs  to 
the  soap-worts  or  the  lilacs  by  the  inspection  of  a 
single  leaf,  when  we  discover  the  horn  of  a  young 
stag,  the  claw  of  a  wild  boar  or  a  wolf,  on  the 
mould  of  a  forest  track,  the  sensation  received  by 


REASONING  IN  PERCEPTION.  73 

our  eye  evokes  the  image  of  objects  which  we  can- 
not at  the  moment  see.  These  operations  are, 
however,  always  of  the  same  kind,  images  suggested 
by  an  actual  sensation,  and  there  is  no  reason  to 
believe  that  the  mechanism  of  this  suggestion  is 
different  in  the  two  cases. 

To  sum  up,  we  may  reduce  all  perceptive  acts 
to  two  types:  specific  recognition  and  individual 
recognition.  It  would  be  interesting  to  know  if 
individual  perception  begins  by  being  generic,  and 
only  gradually  attains,  by  a  regular  progression,  to 
its  complete  development.  According  to  this 
hypothesis,  when  we  see  a  person  whom  we  know,  we 
perceive  him  at  first  as  a  solid  body,  then  as  a  man, 
and  finally  as  such  and  such  a  person.  This  pro- 
gressive development  exists;  it  is  not  only  prob- 
able, it  is  real.  This  is  proved  by  the  following 
experiments  in  hypnotism. 

Among  the  effects  which  suggestion  is  capable 
of  producing  in  a  hypnotized  person  systematized 
anesthesia  is  certainly  one  of  the  most  interesting. 
This  operation  consists  in  rendering  a  person  or  an 
object  invisible  to  the  subject;  it  is,  properly  speak- 
ing, the  isolated  suppression  of  a  particular  percep- 
tion.* 

We  still  remember  the  effects  which  the  first 
experiment  in  anaesthesia  had  on  one  of  our  sub- 
jects, the  said  W .  We  made  this  experiment 

along  with  M.  Fere.  W being  in  the  trance, 

we  suggested  to  her  that  she  would  not  see  M.  Fere 

*Binet  and  F6r6,  Le  transfert  (Revue  philosofhique,  January,  1885). 
An  analysis  of  these  experiments  has  been  published  by  M.  Richer  (op.  fit., 
p.  724  et  seq.). 


74     THE  PSYCHOLOGY  OF  REASONING. 

when  she  awoke,  but  that  she  would  be  able  to  hear 
his  voice.  Upon  her  awakening,  M.  Fere  places  him- 
self before  her;  she  does  not  look  at  him;  he  holds 
his  hand  out  to  her,  but  she  makes  no  gesture. 
She  remains  quietly  seated  in  the  arm-chair  where 
she  had  just  awakened ;  we  are  seated  on  a  chair  by 
her  side.  After  some  time  she  expresses  astonish- 
ment at  not  seeing  M.  Fere,  who  was  then  in  the 
laboratory,  and  asks  us  what  has  become  of  him. 
We  reply:  "He  has  gone  out;  you  may  return  to 
your  ward."  M.  Fere  then  stands  before  the  door. 
The  patient  rises,  bids  us  good-day  and  proceeds 
towards  the  door.  Just  as  she  is  going  to  put  her 
hand  on  the  knob  she  strikes  against  the  invisible 
body  of  M.  Fere.  This  unexpected  shock  makes 
her  tremble;  she  makes  a  fresh  attempt  to  go  on, 
but  meeting  the  same  inexplicable  resistance,  she 
begins  to  be  frightened  and  refuses  to  renew  the 
attempt. 

We  seize  a  hat  which  is  lying  on  the  table  and 
show  it  to  the  patient.  She  sees  it  perfectly  well, 
and  assures  herself,  with  her  eyes  as  well  as  with 
her  hands,  that  it  is  a  real  body.  Then  we  place 
it  on  M.  Fere's  head.  The  hat  appears  to  the 
patient  as  if  it  were  suspended  in  the  air.  Words 
could  not  express  her  astonishment ;  but  her  sur- 
prise reaches  its  climax  when  M.  Fere  lifts  the  hat 
from  his  head  and  salutes  her  several  times;  she 
sees  the  hat,  which  is  sustained  by  nothing,  de- 
scribe a  curve  in  the  air.  At  this  sight  she  declares 
that  "this  is  no  miracle,"  and  supposes  that  this 
hat  is  suspended  by  a  thread.  Thereupon  she  gets 


REASONING  IN  PERCEPTION.  75 

on  a  chair  to  try  and  touch  this  thread,  but  she 
does  not  succeed  in  finding  it.  Then  we  take  a 
cloak  and  hand  it  to  M.  Fer£,  who  puts  it  on.  The 
patient,  who  continues  to  gaze  at  this  cloak  with 
a  look  of  amazement,  sees  it  move  in  the  air  and 
take  the  form  of  an  individual.  "It  is,"  she  says, 
"like  an  empty  manikin."  As  we  speak  the  furni- 
ture moves  and  rolls  noisily  from  one  end  of  the 
room  to  the  other  (it  is  only  the  invisible  M.  Fere 
who  is  displacing  it) ;  the  tables  and  the  chairs  are 
overturned,  then  order  succeeds  to  chaos.  The 
things  are  put  back  in  their  places,  the  de-articulated 
bones  of  a  skull,  scattered  on  the  floor,  are  brought 
together  and  fitted  again ;  a  purse  opens  of  itself, 
and  the  gold  and  silver  pieces  tumble  out  of  it  and  in 
again. 

This  experiment  on  the  invisibility  of  M.  Fere 
had  been  made  on  the  2Oth  of  May,  1884.  At 
the  end  of  the  proceedings  we  omitted  to  render 
M.  Fere  visible,  which  could  have  been  done  by 
hypnotizing  the  patient  again  and  assuring  her 
authoritatively  several  times  that  she  could  see 
M.  Fere.  On  the  23d  of  May  M.  Fere  was  still  invis- 
ible. We  wished  to  bring  this  phenomenon  of 
anaesthesia  to  an  end  by  a  new  suggestion ;  then  we 
observed  a  very  remarkable  thing. 

It  was  first  of  all  found,  to  the  surprise  of  every- 
body, that  the  patient  not  only  ceased  to  see 
M.  Fere,  but  had  lost  all  recollection  of  him,  although 
she  had  known  him  about  ten  years.  She  remem- 
bered neither  his  name  nor  his  existence.  After 
having  put  her  in  the  trance  we  had  considerable 


76  THE  PSYCHOLOGY  OF  REASONING. 

trouble  in  making  M.  Fere  visible  to  her  eyes; 
once  awakened,  she  at  last  saw  his  person  again, 
but,  curiously  enough,  she  did  not  recognize  him, 
and  took  him  for  a  stranger.  It  was  most  comical 
to  see  her  get  angry  when  M.  Fere  thee-and-thou'd 
her  when  speaking  to  her.  Some  days  after,  the 
patient  had  in  the  ward  one  of  the  bad  attacks  of 
hystero-epilepsy  to  which  she  is  unfortunately 
subject.  This  attack  completely  swept  away  the 
last  traces  of  the  anaesthesia,  and  consequently  the 
patient  recognized  M.  Fere  at  last,  without  suspect- 
ing that  during  four  or  five  days  she  had  taken  him 
for  a  stranger  who  was  visiting  the  staff. 

We  find  in  this  last  experiment,*  which  in  a 
manner  happened  by  itself — these  are  the  best — an 
interesting  application  of  the  law  of  retrogression, 
the  importance  of  which,  in  the  destructions  and 
reconstructions  of  the  memory,  has  been  shown  by 
M.  Ribot.  It  is  really  a  general  pathological  law. 
Systematized  anaesthesia  consists,  from  the  psycho- 
logical point  of  view,  in  the  paralysis  of  an  individ- 
ual perception.  Here  we  see  the  anaesthesia  disap- 
pear little  by  little,  by  degrees,  sufficiently  slowly 
to  allow  us  to  perceive  its  progress.  The  patient, 
who  had  at  first  lost  the  perception  of  M.  Fere 
completely,  begins,  under  the  influence  of  a  curative 
suggestion,  by  perceiving  his  person  without  recog- 
nizing it.  The  generic  perception  has  reappeared ; 
the  individual  perception,  which  is  more  complex, 
is  still  paralyzed ;  she  sees  a  man  without  knowing 

•We  mention  only  one  experiment,  but  it  is  not  unique.  It  appears  to 
be  the  rule  that  systematic  anaesthesia  disappears  in  the  manner  indicated. 


REASONING  IN  PERCEPTION.  77 

who  he  is.  Then  the  attack  comes,  one  of  those 
great  internal  catastrophies  which  clear  away  the 
accumulation  of  a  toxic  substance.  Then  the  individ- 
ual perception  reappears, and  recognition  takes  place. 

This  revival  of  the  perception,  which  is  recon- 
structed bit  by  bit,  following  the  order  from  simple 
to  complex,  from  the  general  to  the  individual, 
demonstrates  the  hypothesis  which  we  have  ad- 
vanced ;  the  different  orders  of  perception  which  are 
distinguished  by  the  names  of  generic,  specific  and 
individual  perception,  are  only  the  more  or  less 
advanced  steps  of  one  and  the  same  process.  A 
perfect  continuity  exists  between  the  simplest  per- . 
ceptions,  as  for  example,  the  perception  of  a  colour, 
and  the  complicated  perceptions  which  verge  upon 
logical  and  conscious  reasoning;  and  in  short  a  sin- 
gle act,  in  developing,  in  evolving,  begins  by  being 
a  simple  perception  and  is  transformed  by  degrees 
into  a  complex  reasoning. 

A  comparison  will  bring  this  idea  into  a  graphic 
form.  The  point  of  departure  of  every  perception 
is  an  impression  of  the  senses;  this  initial  element 
is  like  a  nucleus  around  which  layers  of  images  are 
concentrically  arranged.  But  these  layers  are  not 
identical ;  the  images  which  the  sensation  suggests 
first,  and  which  form  the  innermost  and  firmest 
layer,  represent  the  physical  properties  of  the  ob- 
ject, form,  size,  physical  consistence,  weight,  etc., 
and  its  simplest  specific  properties.  The  proof  of 
this  lies  in  the  fact  that  these  properties  are  the 
first  to  be  perceived  when  systematized  anaesthesia 
begins  to  disappear.  On  the  contrary,  the  images 


78     THE  PSTCHOLOGT  OF  REASONING. 

representing  the  individual  characteristics  of  the 
object  constitute  the  most  superficial  and  conse- 
quently the  most  unstable  layer.  Formed  last  of 
all,  they  are  the  first  to  disappear  under  the  influ- 
ence of  an  inhibitory  suggestion. 

We  have  hitherto  considered  only  a  single  aspect 
of  the  percept,  describing  it  as  a  synthesis  of  sensa- 
tions and  images.  From  the  logical  point  of  view, 
the  percept  is  a  judgment,  an  act  which  determines 
a  relation  between  two  facts,  or  in  other  words,  an 
act  which  affirms  something  of  something.  We 
content  ourselves  with  reproducing  an  example 
cited  by  M.  Paulhan  in  a  little  book  which  is  worth 
more  than  many  more  voluminous  works. 

"I  have  a  book  before  my  eyes,  and  I  affirm 
that  it  is  yellow.  If  we  analyze  this  judgment,  we 
find  that  what  I  affirm  is  the  co-existence  of  a  real 
sensation  (the  colour  yellow)  with  other  sensations 
which  I  have  or  can  have  (the  white  colour  of  the 
edges  of  the  book,  the  black  colour  of  the  printed 
letters,  sensations  of  resistance,  of  weight,  etc.). 
But  what  is  the  nature  of  the  act  by  which  I  believe 
these  different  sensations  are  united  together?  There 
is  nothing  in  the  mind  save  the  cohesion  of  these 
different  sensations.  .  .  .  Judgment  therefore 
becomes  reduced  to  an  association  of  images,  for 
the  time  being  indissoluble;  it  is  often  accompanied 
by  an  affirmation  expressed  by  words  thought, 
pronounced  or  written  (a  verbal  proposition),  but  it 
may  exist  independently  of  all  expression ;  it  may 
consist  solely  of  images."* 

*F.  Paulhan,  La  physiologic  de  V esprit,  p.  73. 


REASONING  IN  PERCEPTION.  79 

This  is  the  first  time  we  have  had  to  speak  of 
the  logical  value  of  an  association  of  images.  This 
question  has  been  treated  at  length  by  contempo- 
rary English  psychologists;  we  can  only  refer  to 
their  works,  where  one  will  find  it  established  that 
the  aim  of  all  judgment  is  to  affirm  a  relation  of 
resemblance,  co-existence  or  of  sequence  between 
two  things;*  that  this  affirmation,  this  belief,  this 
judgment,  are  the  external  effects  of  an  internal 
fact,  the  association  of  images  present  to  our 
minds  ;f  and  that,  finally,  as  a  general  conclusion, 
every  time  that  two  images  are  closely  associated, 
as  for  example,  the  image  of  a  stone  thrown  in  the 
air  and  the  image  of  its  fall,  or  even  indissolubly 
associated  like  the  image  of  a  thing  possessing 
resistance  and  the  image  of  a  thing  possessing  ex- 
tension, we  believe  that  the  things  thus  bound 
together  in  our  mind  are  bound  together  in  the  same 
fashion  in  reality.:}:  This  amounts  to  saying  that 
we  exteriorize  an  association  of  images  as  we  exte- 
riorize an  image. 

III. 

We  have  just  seen  that  the  percept  is  a  compli- 
cated structure,  made  up  of  sensations  and  images, 
and  evidently  formed  of  several  layers.  We  are 
already  a  long  way  from  the  common  opinion, 
according  to  which  the  function  of  the  mind  which 
perceives  an  object  is  that  of  the  sensitive  plate  of  a 

*J.  S.  Mill,  Logic,  pp.  71  and  73. 

tH.  Spencer,  Principles  of  Psychology,  Vol.  II,  p.  426. 

tJ.  S.  Mill,  Examination  of  Sir  William  Hamilton's  Philosophy. 


So          THE  PSTCHOLOGT  OF  REASONING. 

photographic  apparatus ;  in  proportion  as  we  get  still 
nearer  to  the  heart  of  our  subject,  we  shall  be  more 
and  more  convinced  of  the  insufficiency  of  that  com- 
parison. 

We  have  several  times,  in  alluding  to  the  psy- 
chological nature  of  perception,  seen  in  it  the  result 
of  unconscious  reasoning.  Although  this  point  is 
generally  admitted  by  contemporary  psychologists, 
save  for  some  variations  and  some  minor  reserva- 
tions, it  forms  too  important  a  part  of  our  subject 
to  allow  us  to  accept  it  without  discussion  and 
without  proof.  This  is  a  question  which  deserves 
to  be  attacked  directly. 

Before  discussing  a  problem,  its  terms  must  be 
very  accurately  stated.  We  do  not  intend  to  com- 
pare perception  with  formal  reasoning  in  all  par- 
ticulars. It  is  plain,  if  the  proposition  be  under- 
stood in  that  sense,  that  what  we  are  maintaining 
becomes  a  paradox.  It  is  paradoxical  to  maintain 
that  the  act  of  recognizing  an  object  by  sight  or 
touch  resembles  a  syllogism.  Therefore  we  do  not 
go  so  far  as  that;  and  the  reason  why  we  dwell 
upon  this  matter  is  in  order  to  beg  our  critics  not  to 
attack  us  by  trying  to  refute  what  we  have  never 
said.  What  we  do  say,  what  we  believe  to  be 
true,  and  what  we  shall  proceed  to  demonstrate,  is 
that  in  formal  reasoning  there  are  essential  charac- 
teristics which  we  again  find  in  external  perception ; 
that  these  two  acts,  so  dissimilar  in  appearance, 
have  yet  the  same  internal  structure,  the  same 
ossature.  To  employ  a  comparison  drawn  from 
natural  history,  external  perception  is  an  act  of 


REASONING  IN  PERCEPTION.  81 

reasoning  in  the  same  way  as  the  amphioxus,  which 
has  no  vertebrae,  is  a  vertebrate. 

To  demonstrate  this  proposition,  we  may  take 
at  hazard  an  example  of  external  perception  and 
an  example  of  formal  reasoning,  and  compare  the 
two.  Let  us  compare  the  perception  of  an  orange 
with  the  familiar  syllogism  of  the  schools:  All  men 
are  mortal;  Socrates  is  a  man,  Socrates  is  mortal. 

When  we  look  at  an  orange  we  experience  a  cer- 
tain number  of  impressions.  There  is  at  first  a 
visual  impression  of  colour,  of  lights  and  shades, 
formed  really  by  a  very  complex  aggregate  of  sim- 
ple sensations.  The  muscular  apparatus  of  the 
eye,  awakened  by  the  excitation  of  the  retina, 
becomes  the  seat  of  contractions  which  are  accom- 
panied by  definite  muscular  sensations ;  the  contrac- 
tion of  the  pupillary  opening,  the  convergence  of 
the  axes  of  the  two  eyes,  the  contraction  of  the 
muscle  of  focal  adaptation,  the  movements  of  the 
eyes  in  their  sockets,  etc.,  must  be  noted;  there 
are  also  the  movements  of  the  head,  neck  and  trunk, 
which  are  unconsciously  performed  so  as  to  allow 
the  luminous  rays  to  reach  the  surface  of  the  retina 
and  the  most  sensitive  part  of  that  surface — that  is 
to  say,  the  yellow  .spot.  These  are  almost  all  the 
real  sensations  which  we  receive  from  the  object  or 
in  connection  with  the  object;  everything  else 
about  it  is  indirectly  known,  in  the  state  of  images. 

Thus  the  direction  and  the  distance  of  the  object 
— that  is  to  say,  its  position  in  space — and  its  size, 
are  three  important  facts  furnished,  not  by  the 
senses,  but  by  the  mind.  This  is  not  all.  We 


82     THE  PSrCHOLOGT  OF  REASONING. 

believe  we  see— that  is  to  say,  we  see  by  the  mind's 
eye— the  spherical  form  of  the  orange,  its  glossy 
and  dotted  surface,  the  juice  which  it  contains,  the 
complicated  arrangement  of  its  internal  parts,  the 
presence  of  seeds,  and  at  the  same  time  we  believe 
we  feel  its  weight,  its  slightly  elastic  consistence, 
its  odour,  its  taste,  and  we  believe  we  hear  its  name 
pronounced. 

If  we  continue  to  look  at  the  orange,  we  induce 
the  revival  of  images  relating  to  its  practical  utility, 
to  the  act  of  cutting  it  with  a  knife,  of  carrying  it 
to  the  mouth,  of  sucking  it  and  throwing  away  the 
pulp  and  the  pips. 

In  short,  there  is  an  immense  number  of  images 
which  cannot  even  be  mentioned  because  they  are 
personal  to  each  observer,  and  dependent  upon  his 
past  experience  and  his  scientific  education.  All 
these  images  are  revived,  to  whatever  degree,  by  the 
presence  of  the  object,  and  gravitate  around  that  sim- 
ple impression  of  a  yellow  spot,  received  by  the  eye. 

In  a  subject  whose  actions  have  been  rendered 
entirely  automatic,  this  suggestion  of  images  by  an 
exterior  object  is  so  powerful  that  it  translates 
itself  outwardly  in  a  series  of  acts.  We  give  an 

umbrella   to  Wit ,    when    she   is   in  a  state  of 

somnambulism;  she  takes  it,  and  she  immediately 
shivers  as  if  she  felt  the  approach  of  the  storm; 
then  she  opens  it  and  begins  to  walk  in  the  labora- 
tory, tucking  up  her  skirt  and  looking  at  her  feet ; 
from  time  to  time  she  jumps  a  streamlet.  The 
scene  is  an  exceedingly  curious  one.* 

*For  other  examples  see  Richer,  op.  cit.,  p,  692  et  seq. 


REASONING  IN  PERCEPTION.  83 

If  we  now  compare  the  perception  of  an  orange 
with  an  act  of  formal  reasoning  having  as  its 
object  the  death  of  Socrates,  what  analogy  will  be 
discovered? 

First. — It  is  hardly  necessary  to  remark  that 
these  two  acts  belong  to  indirect  and  secondary 
knowledge.  When  we  assert  the  future  death  of 
a  living  person,  basing  our  assertion  on  the  death 
of  other  men,  our  assertion  anticipates  the  course  of 
events;  it  is  a  prevision.  In  the  same  way,  when 
we  look  at  an  orange  and  affirm,  explicitly  or  im- 
plicitly, it  does  not  matter  much,  that  "this  is  an 
orange,"  we  pass  beyond,  by  a  mental  act,  the 
limit  of  our  actual  experience.  This  is  precisely 
what  the  preceding  analysis  aimed  at  showing. 
The  characteristics  of  structure,  weight,  taste,  etc., 
attributed  to  an  orange  are  not  comprised  in  the 
visual  impression  which  comes  from  the  orange;  to 
assert  their  existence  is  therefore  to  go  beyond  the 
sensation,  to  accomplish  an  act  which  depends  upon 
indirect  knowledge.  Every  perception  resembles 
a  reasoned  conclusion ;  it  contains,  like  the  logical 
conclusion,  a  decision,  an  affirmation,  a  belief, 
relating  to  a  fact  which  is  not  directly  known  by 
the  senses ;  it  is,  in  other  words,  a  transition  from 
a  known  fact  to  an  unknown  fact. 

Second. — The  two  acts  which  we  are  comparing 
have  a  common  feature  in  implying  the  existence 
of  certain  anterior  intellectual  states — that  is  to 
say,  of  recollections.  In  formal  reasoning,  these 
preparatory  states  are  called  premisses.  Without 
premisses,  there  can  be  no  conclusion.  Our  mind 


84     THE  PSTCHOLOGT  OF  REASONING. 

only  accepts  this  proposition,  "Socrates  is  mortal," 
because  it  knows  the  truth  of  a  different  propo- 
sition, "All  men  are  mortal."  Here  there  is,  be- 
sides, a  distinctive  characteristic  of  all  the  indirect 
processes  of  knowledge;  being  indirect,  they  neces- 
sarily demand  a  proof.  It  matters  little  whether 
this  proof  be  or  be  not  present  to  the  mind  at  the 
moment  when  we  make  use  of  it;  what  is  sufficient 
and  essential  is  that  we  should  have  known  it. 
Thus  there  are  many  simplified  acts  of  reasoning 
whose  premisses  are  unconscious.  The  majority  of 
the  inferences  which  we  make  daily  for  the  practical 
needs  of  life  are  of  this  nature.  Mr.  Spencer  gives 
an  interesting  example. 

"It  is  stated  that  Mr.  So-and-so,  who  is  ninety 
years  old,  is  about  to  build  a  new  mansion ;  and 
you  instantly  laugh  at  the  absurdity — a  man  so 
near  death  making  such  preparation  for  life.  But 
how  came  you  to  think  of  Mr.  So-and-so  as  dying? 
Did  you  first  repeat  to  yourself  the  proposition,  'All 
men  must  die?'  Nothing  of  the  kind.  Certain 
antecedents  led  you  to  think  of  death  as  one  of  his 
attributes,  without  previously  thinking  of  it  as  an 
attribute  of  mankind  at  large.  To  any  one  who 
considered  Mr.  So-and-so's  folly  not  manifest,  you 
would  probably  say,  '  He  must  die,  and  that  very 
shortly,'  not  even  then  appealing  to  the  general 
fact.  Only  on  being  asked  why  he  must  die,  would 
you  either  in  thought  or  word  resort  to  the  argu- 
ment, 'All  men  die,  therefore  So-and-so  must  die.'  " 

We  know,  according  to  Mr.  Spencer,  that  the 
syllogism  represents,  not  the  process  by  which  the 


REASOA'ING  IN  PERCEPTION.  85 

conclusion  is  reached,  but  the  process  by  which  it 
is  justified;  in  other  words,  the  syllogism,  by  con- 
veniently exhibiting  the  data  of  an  act  of  reason- 
ing, enables  us  to  see  whether  we  are  asserting 
more  than  we  absolutely  know,  and  whether  the 
conclusion  is  really  involved  in  the  premisses,  as  we 
suppose  it  to  be.  The  example  quoted  explains 
this  theory. 

Returning  now  to  the  perception  of  an  orange, 
we  shall  have  no  trouble  in  proving  that  this  act 
demands,  as  does  an  act  of  reasoning,  logical  ante- 
cedents. What  our  eye  lets  us  know  directly  is  the 
impression  of  a  yellow  spot ;  no  one  will  maintain 
that  we  are  able,  apart  from  all  experience,  and  by 
a  kind  of  pre-established  mechanism,  to  conclude 
from  this  sensation  that  there  is  an  orange  in  our 
hand,  a  fruit  which  we  may  cut,  eat,  suck,  and 
which  quenches  thirst,  etc.  If  no  experience  had 
ever  intervened,  our  intellect  would  see  nothing 
beyond  our  actual  sensation,  and  there  would  be 
no  perception,  in  the  proper  sense  of  the  word.  If, 
on  the  contrary,  we  are  able  to  recognize  the 
orange,  it  is  because  our  eye  has  received  previous 
education ;  it  is  because  we  have  learned  to  associ- 
ate, on  other  occasions,  a  certain  visual  impression 
(the  sight  of  the  orange)  with  all  the  other  impres- 
sions which  we  formerly  experienced  when  we  took 
the  orange  in  our  hands  to  cut  and  eat  it. 

This  is  therefore  the  second  point  of  contact 
between  the  perception  of  an  exterior  object  and 
an  act  of  reasoning.  These  two  acts  imply  older 
states,  recollections.  These  logical  antecedents  are 


86  THE  PSYCHOLOGT  OF  REASONING. 

called  premisses  in  reasoning  and  anterior  experiences 
in  perception.  The  premiss  of  the  reasoning 
analyzed  is,  "All  men  are  mortal."  That  of  per- 
ception might  be,  strictly  speaking,  formulated  in 
an  analogous  fashion:  "All  spherical  bodies  of 
yellow  colour  and  of  a  certain  size  are  fruits  filled 
with  a  sweet  juice."  However  that  may  be,  we 
see  that  perception  consists,  like  reasoning,  in  the 
application  of  a  recollection  to  the  knowledge  of  a 
new  fact,  and  ends  in  the  generalization  of  this 
recollection. 

But  that  is  not  all. 

If  in  the  majority  of  reasonings  the  premisses 
remain  unconscious,  in  all  or  almost  all  cases  of  per- 
ception, the  anterior  experiences  which  render 
them  possible  are  recalled  to  the  mind  as  little. 
Thus,  when  we  see  a  certain  yellow  spot,  we  imme- 
diately affirm  "this  is  an  orange;"  there  is  no  con- 
scious return  towards  the  past,  and  consequently 
no  allegation  of  proof.  It  is  only  if  we  throw 
doubt  upon  the  accuracy  of  our  perception  that  we 
invoke  our  past  experience,  exactly  as  in  our  every- 
day experiences. 

Third. — We  proceed  with  our  parallel  to  see  how 
far  it  is  justified.  We  know  that  the  foundation 
of  all  reasoning  is  the  recognition  of  a  similitude; 
reasoning  may  be  roughly  defined  as  the  transition 
from  a  known  fact  to  a  second  unknown  fact,  by 
means  of  a  resemblance.  When  we  mentally  read 
over  the  following  syllogism,  "All  men  are  mortal; 
Socrates  is  a  man,  therefore  Socrates  is  mortal," 
we  pass  from  a  known  fact  (the  mortality  of  men) 


REASONING  IN  PERCEPTION.  87 

to  an  unknown  fact  (the  death  of  Socrates),  by 
virtue  of  the  relation  of  resemblance  which  we 
discern  between  the  two  facts;  this  resemblance 
forms  the  object  of  a  special  proposition,  "Socrates 
is  a  man. ' '  There  is  no  act  of  reasoning  in  the  world 
which  does  not  contain,  after  the  manner  of  this 
example,  the  affirmation  of  a  resemblance;  but 
this  affirmation  takes  different  forms  and  is  called 
by  different  names:  comparison,  classification, 
recognition,  etc.  We  even  know  that  the  school 
of  Aristotle  compares  reasoning  to  a  classification. 
To  conclude  that  Socrates  is  mortal  would  be  to 
put  Socrates  in  the  class  of  men,  of  whom  mortality 
is  an  attribute. 

The  perception  of  an  exterior  object  implies  a 
similar  act  of  identification.  In  order  to  recognize, 
with  the  sight  alone,  that  we  have  before  us  an 
orange,  it  is  not  enough  that  past  experiences  should 
have  formed  an  association  between  a  piece  of  yel- 
lowish-red colour  and  certain  characteristics  of 
structure,  touch,  taste  and  weight;  it  is  necessary, 
in  addition,  that  a  resemblance  should  exist  between 
the  two  experiences,  past  and  present;  it  is  neces- 
sary that  the  two  pieces  of  colour  should  have  the 
same  colour,  the  same  tint.  We  do  not  generally 
reflect  in  order  to  assure  ourselves  of  this  resem- 
blance by  a  voluntary  act  of  comparison ;  but  it  is 
none  the  less  true  that  it,  the  resemblance,  must 
exis-t.  Further,  we  are,  in  the  majority  of  cases, 
very  quick  to  distinguish  a  real  resemblance  from  a 
deceptive  analogy. 

Some  authors  have  also  compared  perception  to 


88  THE  PSTCHOLOGT  OF  REASONING. 

an  operation  of  classifying,  as  has  been  done  in  the 
case  of  logical  reasoning.  According  to  them,  the 
visual  perception  of  an  object  would  consist  of 
classing  the  sensation  which  we  experience  in  the 
group  of  analogous  sensations  which  have  formerly 
been  experienced.  This  idea  has  been  developed 
at  length  by  Mr.  Spencer. 

In  short,  perception  and  reasoning  have  the 
three  following  characteristics  in  common:  First, 
they  belong  to  mediate  and  indirect  knowledge; 
second,  they  require  the  intervention  of  truths  for- 
merly known  (recollections,  facts  of  experience, 
premisses);  third,  they  imply  the  recognition  of  a 
similitude  between  the  fact  affirmed  and  the  ante- 
rior truth  upon  which  it  depends.  The  union  of 
these  characteristics  shows  that  perception  is  com- 
parable to  the  conclusion  of  logical  reasoning.* 

This  is  one  of  those  truths  which  have  been  so 
fully  demonstrated  that  they  have  found  their  way 
into  every  book.  Helmholtz  says  in  this  connec- 
tion: The  judgments  by  which  we  trace  sensations 
back  to  their  causes  belong,  by  their  results,  to  what 
are  called  judgments  by  induction  ;f  and  in  support 
of  this  contention,  he  cites  the  following  example: 
"As  in  the  immense  majority  of  cases  the  excita- 

*We  may  remark  that  the  existence  of  so  many  different  definitions  of 
reasoning  is  due  to  the  fact  that  each  of  them  considers  only  one  of  the  fore- 
mentioned  characteristics.  Thus,  the  following  definition:  reasoning  is  a 
transition  front  the  known  to  the  unknown,  or  again,  reasoning  is  a  demon- 
stration, relates  to  the  first  characteristic;  the  definition:  reasoning-  is  an 
extension  of  knowledge  already  attained,  relates  to  the  second;  and  the 
definition:  reasoning  is  a  classification,  relates  to  the  third. 

•(•Induction  is  inaccurate.  In  perception,  the  mind  never  rises  so  high  as 
a  general  conclusion;  it  simply  comes  to  a  conclusion  on  the  object  present 
to  the  senses.  It  is  an  inference  from  particular  to  particular,  and  likewise, 
in  the  case  where  perception  is  aided  by  a  considerable  number  of  anterior 
experiences,  it  is  a  deduction. 


REASONING  IN  PERCEPTION.  89 

tion  of  the  retina  at  the  external  angle  of  the  eye 
comes  from  a  ray  of  light  which  reaches  the  eye 
from  the  nasal  side,  we  think  it  is  the  same  in  every 
new  case  in  which  the  excitation  affects  the  same 
part  of  the  retina,  just  as  we  maintain  that  every 
man  who  is  at  present  living  must  die,  because 
experience  has  taught  us  that  so  far  death  is  the  end 
of  all  men."  We  might  extract  analogous  quota- 
tions from  the  works  of  Mill,  Spencer,  Bain,  etc. 

It  would  be  easy  to  follow  up  and  renew  the 
comparison  which  we  have  made  between  perception 
and  the  syllogism,  by  remarking  that  if  perception 
is  an  act  of  reasoning,  the  illusion  of  the  senses  is  a 
sophism.  This  deduction  was  made  long  ago ;  it 
has  even  been  attempted  to  extract  the  logical  rule 
which  is  violated  by  the  majority  of  illusions.  We 
may  cite  an  example,  borrowing  it  from  the  class  of 
passive  illusions,  which  have  been  very  carefully 
studied  by  Mr.  J.  Sully.*  If  the  ringer  be  pressed 
upon  the  outside  of  the  lowered  eyelid,  a  kind  of 
luminous  ring  will  appear.  This  image,  which 
represents  the  end  of  the  finger,  will  not  be  local- 
ized at  the  point  where  the  retina  has  been  excited, 
but  inside  and  above,  towards  the  upper  part  of  the 
nose,  "just  at  the  place  where  the  luminous  source 
which  affects  the  retina  at  the  place  touched  is 
generally  situated.  The  sophism  contained  in  the 
unconscious  reasoning  consists  in  taking  as  an  abso- 
lute law  a  rule  which  is  only  valid  in  certain  cases. 
Errors  of  this  kind  are  frequently  met  with  in  the 
physiology  of  the  organs  of  the  senses. 

*Op.  cit.,  passim. 


90  TUB  PSTCHOLOGY  OF  REASONING. 

We  may  now  consider  it  as  sufficiently  demon- 
strated that  perception  is  an  act  of  reasoning.  We 
shall  not  therefore  pause  to  discuss  the  opinion  of 
some  thinkers  who  insist  upon  drawing  a  line  be- 
tween reasoning  and  inference,  and  wish  to  see  no 
more  than  an  inference  in  perception.  According 
to  these  writers,  inference  would  be  the  simple  con- 
secution by  which  the  mind  passes  from  one  idea  to 
another,  as  when  a  Dutchman,  traversing  a  town  in 
India,  expects  to  find  a  tavern  in  it;  this  operation, 
though  a  passage  from  the  known  to  the  unknown, 
would  be  only  a  pseudo-reasoning,  a  sketch  which 
does  not  deserve  the  name  of  the  finished  work. 
But  there  is  in  reasoning,  always  according  to  the 
same  writers,  something  more  in  the  mind  than  this 
bringing  together  of  facts.  Reasoning  is  the  reflect- 
ive act  by  which  the  mind  adopts  a  proposition 
because  it  sees  in  it  the  logical  consequence  of 
other  propositions  which  it  holds  to  be  true;  so 
that  the  only  rational  operation  is  that  in  which  all 
the  premisses  are  present  to  the  mind,  and  where 
the  mind  perceives  the  relation  which  binds  the 
premisses  to  the  conclusion.* 

We  reject  this  arbitrary  distinction.  Inference 
or  reasoning,  it  is  always  the  same  thing ;  we  have 
just  shown  this  in  the  case  of  perception,  where 
analysis  reveals  the  essential  parts  of  a  syllogism. 
How  could  it  be  maintained,  after  that  analysis, 
that  perception  is  a  simple  consecution?  All  that 
may  be  granted  is  that  in  reality  certain  reasonings 
are  conscious  and  that  others  are  automatic.  Per- 

*Brochard,  Logique  de  Stuart  Mill,  Revue  philos.,  Vol.  XII. 


REASONING  IN  PERCEPTION.  91 

ception  is  of  the  second  class.  But  great  value 
should  not  be  attached  to  this  difference.  Con- 
sciousness accompanies  the  physiological  processes 
of  reasoning,  of  sensation,  of  recollection,  etc.,  it 
does  not  constitute  them;  it  is  an  epiphenomenon, 
and  nothing  more.*  So  far  as  quantitative  experi- 
ments made  on  sensations  go  to  prove,  conscious- 
ness is  subject  to  conditions  of  duration  and  intens- 
ity. If  these  conditions  are  realized,  it  exists;  if 
not,  it  is  wanting.  But  in  every  case  it  appears 
and  disappears  without  disturbing  the  action  of  the 
nerve  cells,  which  continues  silently  in  the  same 
necessary  way. 

IV. 

We  have  just  seen  that  the  work  involved  in 
every  perception  is  identical  with  the  operation 
which  consists  in  drawing  a  conclusion  when  the 
premisses  are  given.  At  the  same  time  we  made  a 
short  survey  of  the  nature  of  this  work.  Let  us  go 
further,  and  we  shall  try  to  give  an  explanation  of 
reasoning. 

But  before  approaching  this  great  problem,  to 
which  this  book  is  wholly  devoted,  let  us  pause  at 
some  preliminary  considerations.  We  intend  to 
give  a  psychological  theory  of  reasoning.  For 
this  theory  to  be  correct,  for  it  to  be  even  accept- 
able, it  is  evidently  necessary  that  it  should  satisfy 
certain  conditions,  that  it  should  fit  certain 
psychical  facts  already  known  and  considered  as 
certain.  Psychology  is  no  longer  in  that  state  of 

*Ribot,  Diseases  of  the  Memory,  p.  36  (Appleton,  New  York),  and  The 
Diseases  of  Personality,  Introduction  (The  Open  Court  Pub.  Co.,  Chicago). 


92  THE  PSTCHOLOGT  OF  REASONING. 

infancy  which  every  science  has  known  and  in  which 
any  one  may  freely  erect  fantastic  explanations 
which  rest  on  nothing. 

In  every  science  which  has  undergone  organiza- 
tion, a  new  theory  has  a  right  to  be  cited  only 
when  it  is  supported  by  admitted  facts ;  if,  for  ex- 
ample, some  one  pretended  to  have  discovered  per- 
petual motion,  it  would  be  right  to  reject  his  pre- 
tended discovery  without  examination,  for  it  would 
be  contrary  to  all  the  laws  of  mechanics.  Psychol- 
ogy also  has  its  questions  of  perpetual  motion. 
Therefore,  before  seeking  the  solution  of  our  prob- 
lem, let  us  put  it  in  the  form  of  an  equation,  in 
order  to  determine  the  conditions  which  the  solu- 
tion must  satisfy  in  order  to  be  correct. 

First  condition. — Stuart  Mill  remarked  that  all 
psychological  explanations,  Avithout  exception,  are 
subject  to  a  general  condition ;  that  of  being  an 
application  of  the  laws  of  association  by  resemblance 
and  by  contiguity.*  To  explain  a  psychological 
fact  is,  according  to  Stuart  Mill,  to  show  that  it  is 
a  particular  case  of  the  laws  of  association.  We  do 
not  intend  to  inform  the  reader  what  is  understood 
by  these  laws ;  the  subject  is  well  known,  thanks  to 
the  numerous  analyses  of  English  works  which  we 
possess.  We  may  merely  recall  the  fact  that  asso- 
ciation by  resemblance  is  the  law  by  which  ideas, 
images  and  feelings  which  are  alike  are  called  up  in 
the  mind.  Thus,  a  portrait  evokes  the  idea  of  the 
model.  We  may  also  recall  the  fact  that  associa- 
tion by  contiguity  is  the  law  by  which  two  phenom- 

*John  Stuart  Mill,  Dissertations  and  Discussions,  III,  105  et  seq. 


REASONING  IN  PERCEPTION.  93 

ena  which  have  been  experienced  together  tend  to 
associate  themselves  in  our  mind,  so  that  the  image 
of  the  one  recalls  the  image  of  the  other.  Such  are 
the  laws  of  association ;  our  cut-and-dried  formulae 
can  convey  no  idea  of  the  immense  number  of  phe- 
nomena which  these  laws  explain.  However,  no 
one  has  the  right  to  maintain  that  these  laws  are  the 
only  ones,  and  that  no  others  exist.  We  cannot 
imagine  that  we  already  know  all  the  laws  of  mind. 
That  would  be  a  singular  presumption.  So  we 
believe  that  Stuart  Mill  was  too  exclusive  in  saying 
that  all  psychological  explanations  consist  in  reduc- 
ing the  fact  to  be  explained  to  the  laws  of  associa- 
tion. What  must  be  retained  of  Stuart  Mill's 
opinion  is  that  in  psychology,  as  in  all  other  sci- 
ences, an  explanation  ought  to  plead  nothing  out- 
side of  truths  which  are  at  the  same  time  known 
and  established ;  now,  as  the  only  psychological 
laws  which  we  can  at  the  present  time  consider  as 
established  are  those  of  association,  they  are  the 
only  ones  which  we  may  provisionally  introduce 
into  explanations.  There  we  have  a  valuable  sign 
which  enables  us  to  distinguish  at  first  sight  a  seri- 
ous explanation  from  those  caricatures  of  explana- 
tions which  are  merely  hypotheses  built  upon  other 
hypotheses. 

Second  condition. — For  the  psychologist  every 
verbal  proposition  resolves  itself  into  an  association 
of  images,  and  the  demonstration  of  a  proposition, 
the  reasoning,  is  the  creation  of  a  new  association. 
Reasoning  has  been  very  accurately  defined  by  Mr. 
Spencer  as  "the  establishment  of  a  relation  between 


94  THE  PSrCHOLOGT  OF  REASONING. 

two  things,"  and  he  has  explained,  with  a  great 
amount  of  detail,  the  meaning  and  the  range  of  his 
definition. 

We  have  already  had  occasion  to  show  that  in 
every  perception  there  is  work,  and  that  this  work 
culminates  in  a  synthesis  of  sensations  and  images.* 
The  process  of  perceiving  an  object,  for  example  an 
orange,  and  of  recognizing  the  existence  and  nature 
of  that  fruit  when  placed  before  us,  consists  in 
associating  with  a  visual  impression  a  certain  num- 
ber of  attributes  of  which  we  do  not  take  direct 
cognizance;  but  to  associate  two  groups  of  quali- 
ties, is  to  judge;  it  is,  as  Mr.  Spencer's  definition 
has  it,  to  establish  a  relation  between  two  things. 

This  settled,  the  following  question  arises: 
How  is  this  synthesis  formed?  By  what  process  is 
a  relation  established  between  the  two  things? 
How  do  we  pass  from  an  impression  of  yellowish-red 
colour  received  by  the  eye  to  the  image  of  all  those 
attributes  which  characterize  an  orange?  Or  again 
(for  we  are  anxious  to  show  all  the  aspects  of  the 
problem),  how  do  we  judge  that  "this  is  an  orange?" 
Third  condition. — Mr.  Spencer  adds  a  word  to 
the  definition  of  reasoning  already  quoted.  Rea- 
soning, he  says,  is  the  indirect  establishment  of  a 
relation  between  two  things.  This  adjective  will 
be  fully  understood  by  means  of  an  example.  Let 
us  suppose  that  instead  of  confining  ourselves  to 
looking  at  the  orange,  we  took  hold  of  the  fruit  and 
occupied  ourselves  in  peeling  and  eating  it.  Accord- 
ing as  we  perform  these  different  actions,  an  associ- 

*See  pages  70  and  81. 


REASONING  IN  PERCEPTION.  95 

ation  becomes  formed  in  our  mind  between  the 
sight  of  the  orange  and  innumerable  sensations  of 
the  hand  and  of  taste;  the  formation  of  this  rela- 
tion is  direct,  produced  by  experience,  it  comes 
from  without.  On  the  contrary,  when  we  perceive 
the  orange  at  a  distance,  without  touching  it — that 
is  to  say,  when  we  reason  regarding  our  visual  sen- 
sation— the  relation  which  is  established  between 
this  sensation  and  the  mental  image  of  the  attri- 
butes is  indirect,  in  the  sense  that  it  is  not  produced 
by  actual  experience,  and  that  it  is  produced  by  the 
operation  of  other  intellectual  states — premisses. 

Let  us  express  this  fact  in  the  precise  language 
of  psychology.  What  is  a  premiss?  It  is  a  judg- 
ment, an  association  of  images.  Consequently, 
what  is  a  conclusion  which  follows  from  the  prem- 
isses? It  is  an  association  of  images  produced  by 
other  associations. 

We  may  therefore  formulate  as  follows  the  third 
question  which  arises:  How  can  the  two  complete 
associations  forming  the  premisses  unite  to  form  a 
third,  that  which  constitutes  the  conclusion  of  the 
reasoning? 

We  possess  the  touchstone  with  which  we  may 
make  sure  whether  a  psychological  theory  of  reason- 
ing is  true  or  false.  Let  us  try  this  criterion. 

Very  few  of  the  existing  theories  of  reasoning 
are  in  harmony  with  modern  ideas  and  merit  discus- 
sion. The  spirtualistic  French  school,  which  has 
on  many  questions  adhered  to  the  old  doctrine  of 
entities,  generally  explains  reasoning  by  a  faculty  of 
reasoning;  some  supporters  of  this  school  are  not 


96     THE  PSTCHOLOGT  OF  REASONING. 

content  with  this  purely  verbal  explanation,  but 
they  confine  themselves  to  maintaining  that  reason- 
ing is  a  simple,  irreducible  and  consequently  inex- 
plicable property.  It  is  to  be  regretted  that 
M.  Taine,  in  his  magnificent  work  On  Intelligence, 
gave  us  a  theory  of  knowledge  instead  of  a  psychol- 
ogy of  reasoning.  In  Germany,  Wundt  places  rea- 
soning at  the  basis  of  the  psychical  life ;  he  makes  it 
the  foundation  of  all  our  thoughts,  and  goes  as  far 
as  to  say  that  we  might  call  the  mind  "a  thing 
which  reasons."  Thus  he  tries  to  discover  reason- 
ing even  in  the  primitive  and  elementary  fact  of 
the  psychical  life,  in  sensation.  But  when  it  comes 
to  taking  the  mechanism  of  reasoning  to  pieces,  bit 
by  bit,  to  explain  it  according  to  known  laws,  a 
gap  is  visible  in  his  work.  As  far  as  we  are  able  to 
judge,  in  the  light  of  M.  Ribot's  analyses,  which 
are  always  masterpieces,  Wundt  has  not  given  us 
an  explanation  of  reasoning.  In  England,  Stuart 
Mill  concerns  himself  almost  exclusively  with  the 
logic  of  reasoning,  he  leaves  psychology  alone ;  and 
we  know  that  there  is  as  much  difference  between 
psychology  and  logic  as  between  physiology  and 
hygiene.  Alexander  Bain,  who  systematically 
reduces  all  mental  states  to  a  combination  of  the 
la\vs  of  association,  touches  several  times  upon  the 
question  which  engages  us;  but  his  thought  re- 
mains vague  and  irresolute,  and,  yielding  to  his 
habit,  he  describes  instead  of  explaining.*  Only 
in  Mr.  Spencer's  work  do  we  find  a  true  theory  of 
reasoning. 

*See  especially,  in  his  excellent  book  on   The  Senses  and  the  Intellect, 
pages  524  et  seq. 


REASONING  IN  PERCEPTION.  97 

In  this  case  the  theory  is  as  complete  as  could 
be  wished,  for  it  starts  from  the  most  elevated  type 
of  reasoning  and  reaches  the  simplest,  including  in 
its  immense  span  compound  quantitative  reasoning, 
simple  and  imperfect  quantitative  reasoning,  perfect 
qualitative  reasoning,  imperfect  qualitative  reason- 
ing, reason  in  general,  perception,  and  the  feeling 
of  resistance.  The  author  has  tried  to  prove  that 
the  process  which  the  philosopher  follows  in  his 
longest  and  most  complicated  reasonings  is  that  by 
which  incipient  consciousness  strives  to  become 
thought;  that,  in  a  word,  a  unity  of  composition 
exists  among  all  the  phenomena  of  the  intellect. 
What  is  this  unity?  The  whole  study  of  reasoning 
may  be  summed  up  by  defining  it  as  "a  classifica- 
tion of  relations."  But  what  does  the  word  classi- 
fication signify?  It  signifies  the  act  of  grouping 
together  like  relations.  To  deduce  a  relation  is  to 
think  that  it  is  like  certain  others.* 

Before  this  theory  is  discussed  it  must  be  made 
clear.  We  shall  do  this  by  quoting  from  the  author 
some  types  of  reasoning,  and  by  showing  how  the 
idea  of  a  classification  of  relations  throws  light  upon 
the  mechanism  of  these  operations. 

Let  us  take  as  an  example  an  "imperfect  quali- 
tative reasoning,"  which  treatises  on  logic  com- 
monly give  as  a  syllogism.  When  we  say,  "All 
horned  animals  are  ruminants;  this  is  a  horned 
animal,  therefore  this  animal  is  a  ruminant,"  the 
mental  act  indicated  is,  according  to  Mr.  Spencer, 
a  cognition  of  the  fact  that  the  relation  between  the 

*Half  of  the  second  volume  of  The  Principles  of  Psychology  is  devoted 
to  the  development  of  this  question. 


98  THE  PSYCHOLOGY  OF  REASONING. 

particular  attributes  in  this  animal  is  like  the  rela- 
tion between  the  homologous  attributes  in  certain 
other  animals.  It  may  be  symbolized  thus : 


(The  attributes  const;- 
luting  a  horned  ani-  A 
mal.) 


(coexist  with) 

(The  attributes  consti- 
tuting a  ruminating 
animal.) 


B 


(The  attributes  consti- 
tuting  this  a  horned 
animal.) 

is  like -j  (coexist  with) 

(The   attributes    consti- 
b      tuting  this  a  ruminat- 
ing animal.) 


"The  relation  between  A  and  B  is  like  the  rela- 
tion between  a  and  b;"  such  is  the  formula  which, 
according  to  the  author,  really  represents  our  log- 
ical intuition.  It  will  be  noticed  that  reasoning 
thus  understood  becomes  a  true  proportion,  with 
four  terms,  a  kind  of  rule  of  three  from  which  the 
idea  of  quantity  is  excluded.  Stuart  Mill  has 
reproached  Mr.  Spencer  for  making  reasoning  an 
operation  in  four  terms,  and  he  has  maintained 
that  in  reality  only  three  exist.  Thus,  to  transfer 
the  controversy  to  the  preceding  example,  Stuart 
Mill  has  remarked  that  the  reasoning  attributes  to  a 
certain  animal  which  has  horns  the  same  attributes 
(constituting  the  ruminating  animal)  as  to  all  the 
other  animals  which  have  horns;  consequently,  the 
two  terms  indicated  by  the  letters  B  and  b  make 
only  one,  they  are  the  same;  three  terms  exist  and 
not  four.  Mr.  Spencer  has  replied  that  as  these 
attributes  do  not  belong  to  the  same  animals,  but 
to  distinct  though  similar  animals,  the  attributes 
also  ought  to  be  distinct.  The  solution  of  this 
difficulty  is  easy  to  find ;  it  seems  to  us  that  Mill  is 


REASONING  IN  PERCEPTION.  99 

right.  He  would  have  been  able  to  reply  to  Mr. 
Spencer:  Every  horned  beast  has  distinct  attri- 
butes which  make  it  a  ruminant,  but  the  general 
idea  which  we  have  of  these  attributes  is  common  to 
these  animals;  it  is  the  same  for  all.  And  thus  we 
succeed  in  reducing  the  terms  of  the  reasoning  to 
three.* 

That,  however,  is  a  trifling  matter.  Let  us 
admit  for  a  moment  the  existence  of  the  four  terms. 
It  may  be  granted  that  reasoning  is  a  classification 
of  relations;  but  the  relations  must  be  formed  be- 
fore they  can  be  classed,  for  they  do  not  exist 
before  being  formed,  and  we  cannot  compare  what 
does  not  exist.  The  curious  thing  is  that  this  im- 
portant question  is  hardly  touched  upon  by  Mr. 
Spencer,  and  yet  he  was  the  first  to  recognize  that 
reasoning  consists  in  the  establishment  of  a  relation. 
The  few  words  which  he  has  written  on  this  sub- 
ject, as  if  by  the  way,  relate  to  another  example. f 
Analyzing  the  following  syllogism,  "All  crystals 
have  planes  of  cleavage ;  this  is  a  crystal,  therefore 
this  has  a  plane  of  cleavage,"  he  inquires  how  our 
mind  is  able  to  pass  from  the  perception  of  an  indi- 
vidual crystal  to  the  idea  of  a  plane  of  cleavage; 
and  he  prefers  to  say,  in  order  to  explain  the  estab- 
lishment of  a  relation  between  these  two  things, 
which  is  the  essential  difficulty  of  the  question: 
"Before  consciously  asserting  that  all  crystals  have 
planes  of  cleavage  it  has  already  occurred  to  me 
that  this  crystal  has  a  plane  of  cleavage."  But 
then,  it  may  be  objected,  everything  is  done;  the 

*Spencer,  Principles  of  Psychology,  Vol.  II,  p.  69. 
\Op.  fit.,  p.  97,  Vol.  II. 


ioo      THE  psrciiOLOGT  OF  REASONING. 

work  of  reasoning  is  accomplished,  the  relation  is 
established,  and  it  is  precisely  all  this  which 
required  explanation.  Mr.  Spencer  himself  recog- 
nizes this,  for  he  calls  this  operation,  which  he 
assumes  to  be  effected  without  explaining  its  gen- 
esis, a  primary  or  provisional  inference.  ' '  This  act 
is  simple  and  spontaneous,"  he  says,  "resulting  not 
from  a  remembrance  of  the  before-known  like  rela- 
tions, but  merely  from  the  influence  which  as  past 
experiences  they  exercise  over  the  association  of 
ideas."*  Therefore  we  see  that  when  it  comes  to 
the  decisive  moment,  the  theory  disappears;  it  can- 
not be  declared  to  be  either  true  or  false,  for  it  does 
not  really  exist. 

We  have  still  many  other  objections  to  offer. 
We  might  ask  what,  in  this  comparison  of  relations, 
the  old  relation,  that  which  takes  the  place  of 
premisses,  can  add  to  the  new  and  inferred  relation. 
When  I  assert  that  a  relation  exists  between  the 
crystal  which  I  hold  and  a  plane  of  cleavage,  I  find, 
it  is  true,  a  confirmation  of  what  I  assert,  in  repre- 
senting this  old  relation  to  myself:  All  crystals 
have  planes  of  cleavage.  The  general  rule  proves 
the  particular  case.  But  it  is  precisely  this  which 
wants  explanation.  We  have  just  shown  this  in 
stating  the  equation  of  a  theory  of  reasoning;  the 
reader  will  recollect  that  we  made  this  point  the 
third  condition  which  a  theory  of  reasoning  must 
fulfill  in  order  to  be  correct.  It  must  be  explained, 
we  have  said,  how  a  conclusion  follows  from  its 
premisses;  in  more  accurate  language,  it  must  be 

*Op,  cit.,  Vol.  II,  p.  102. 


REASONING  IN  PERCEPTION.  IOI 

shown  how  an  association  between  two  terms  can  be 
formed  by  the  medium  of  former  associations.  But 
Mr.  Spencer's  hypothesis  is  powerless  to  solve  this 
question.  What  does  he  tell  us?  That  the  mind, 
after  having  formed  (it  is  not  known  how)  a  relation 
between  a  and  b,  compares  it  to  a  before-known 
relation  between  A  and  B.  But  what  can  follow 
from  this  intuition  of  a  resemblance  between  the 
two  relations?  How  can  the  comparison  of  the  two 
add  to  the  bond  which  already  unites  the  terms  a 
and  b?  This  is  a  question  of  mental  mechanism 
which  has  to  be  solved.  Mr.  Spencer  does  not 
solve  it,  he  does  not  even  suspect  it.  It  is  one  of 
the  characteristics  of  the  theory  we  are  discussing 
that  it  does  not  touch  this  question.  Mr.  Spencer 
confines  himself  to  proving  that  the  idea  that  all 
crystals  have  planes  of  cleavage  confirms  the  partic- 
ular conclusion,  this  crystal  has  a  plane  of  cleavage ; 
but,  once  more,  this  is  merely  stating  the  question. 
It  would  be  necessary  to  explain  this  confirmation 
of  the  particular  relation  by  the  general  relation 
by  introducing  the  laws  of  association. 

We  are  sorry  to  have  to  deliver  such  a  judgment 
on  a  part  of  the  work  of  a  thinker  who  has  done  so 
much  for  psychology;  but  it  is  a  duty  to  judge 
theories  in  themselves,  without  taking  into  account 
the  fame  of  those  whose  names  are  associated  with 
them. 

We  shall,  in  our  turn,  approach  the  problem  of 
reasoning,  putting  forward  some  observations  on  a 
mental  law  to  which  we  shall  often  appeal,  the  law 
of  resemblance. 


CHAPTER  IV. 

THE   MECHANISM    OF   REASONI]S7G. 


THE  action  of  resemblance  on  the  phenomena  of 
the  mind  has  been,  so  to  speak,  recognized  in  all 
times;  it  has  never  been  very  difficult  to  discover 
that  one  idea  suggests  a  like  one.  Mr.  Bain,  who 
has  devoted  a  long  chapter,  full  of  facts,  to 
association  by  resemblance,  enunciates  in  the  fol- 
lowing terms  the  law  which  governs  this  association : 
"Present  actions,  sensations,  thoughts  or  emotions 
tend  to  revive  their  like  among  previous  impressions 
or  states."*  This  is  a  very  wide  formula,  for  it 
includes  not  only  ideas,  but  emotions  and  actions; 
nevertheless,  it  seems  to  us  to  be  incomplete  upon 
a  most  important  point. 

The  reproductory  action  of  resemblance  —  the 
attraction  of  sameness — is  a  common  and  superficial 
effect,  known  to  us  since  the  days  of  Aristotle  ;f 
resemblance  has  in  reality  a  second  effect,  quite  as 
important  as  the  first — that  of  fusion.  Alongside 
the  law  of  suggestion  and  of  recollection  by  resem- 
blance, we  may  place  the  Law  of  Fusion. 

It  may  be  enunciated  as  follows,  the  demonstra- 

*Bain,  The  Senses  and  The  Intellect^  p.  463  ;  J.  Stuart  Mill,  Examina- 
tion of  Sir  William  Hamilton's  Philosophy,  p.  225;  Cf.  Ribot,  La  psycho- 
logie  anglaise  contemporaine . 

|On  this  subject  Hamilton's  Dissertation  at  the  end  of  his  edition  of 
Reid,  may  be  consulted. 

102 


THE   MECHANISM  OF  REASONING.          103 

tion  being  left  for  later  consideration :  "When  two 
like  states  of  consciousness  are  present  to  our  mind 
simultaneously  or  in  immediate  succession,  they 
become  fused  together  so  as  to  form  a  single  state." 
Thus,  when  two  sounds  of  the  same  pitch  and  the 
same  timbre  vibrate  at  the  same  time,  the  most 
practiced  ear  does  not  dissociate  them ;  only  a 
single  reinforced  sound  is  heard ;  each  sound  loses  its 
individuality  in  a  single  resultant.  If  the  two  states 
of  consciousness  are  exactly  alike,  the  fusion  is  com- 
plete ;  if  they  present  only  an  imperfect  resemblance, 
implying  a  partial  sameness,  the  fusion  is  partial. 

The  fusion  of  like  sensations. — The  best  illustra- 
tion of  our  law  as  regards  sensations  is  furnished  by 
the  sensations  of  touch,  in  Weber's  experiment. 
This  experiment  shows  us  the  fusion  of  like  sensa- 
tions; they  fuse  so  thoroughly  that  a  person  who 
has  not  been  told  beforehand  that  he  is  receiving 
two  sensations  produced  by  two  distinct  excitations 
believes,  while  he  experiences  only  a  single  sensation, 
that  his  skin  is  bearing  only  a  single  pressure. 
But  this  phenomenon  touches  upon  a  much  dis- 
cussed problem  in  physiology,  upon  which  we  must 
first  of  all  say  some  words  of  explanation. 

Among  all  the  senses,  touch  is  the  one  which 
occupies  the  largest  surface ;  while  the  special  senses, 
sight,  hearing,  smell  and  taste,  are  confined  to  ex- 
tremely small  parts  of  the  organism,  that  of  touch 
is  found  over  the  whole  extent  of  the  skin  and 
even  on  some  mucous  membranes ;  the  nasal  fossae, 
the  conjunctiva,  the  buccal  cavity,  the  two  extrem- 
ities of  the  digestive  tube,  and  the  urethral  canal 


104         THE  PSTCHOLOGT  OF  REASONING. 

give  us  sensations  of  contact.  This  wide  diffusion 
of  the  sense  of  touch  over  the  surface  of  the  body 
is  explained  by  the  fact  that  touch  is  the  funda- 
mental and  primitive  sense  from  which  the  special 
senses  have  been  derived  by  a  progressive  differenti- 
ation, and  which  perhaps  will,  in  the  course  of 
time,  give  rise  to  the  formation  of  new  special 
senses.  The  sense  of  touch  is  not  equal  all  over; 
certain  divisions  of  the  general  epidermis  display  a 
delicacy  superior  to  that  of  the  others.  For  ex- 
ample, we  know  that  the  tactile  sensibility  is  dull 
on  the  middle  of  the  back;  it  is  keener  on  the 
hand,  keener  still  on  the  tips  of  the  fingers;  the 
highest  degree  of  sensibility  is  reached  at  the  end  of 
the  tongue.  Weber  succeeded  in  measuring  these 
differences  in  sensibility  by  employing  a  pair  of 
blunt  compasses,  the  two  points  of  which  he  shifted 
over  the  surface  of  the  body.  He  found  that  on 
the  middle  of  the  back  the  two  points  are  not  felt 
double  until  they  are  thirty-nine  lines  apart  (a  line 
=0.88  inch);  when  closer,  the  two  points  produce 
only  a  single  sensation.  On  the  chest  the  necessary 
distance  is  twenty  lines;  on  the  thigh,  sixteen;  on  the 
lower  part  of  the  forehead,  ten;  on  the  palm  of  the 
hand  or  the  end  of  the  nose,  three ;  on  the  edee  of 

o 

the  lower  lip,  two ;  on  the  tip  of  the  index  finger, 
one;  on  the  point  of  the  tongue,  one-half. 

These  experiments  in  measurements  have  given 
rise  to  a  new  problem.  It  has  been  asked  why  two 
compass  points  produce,  according  to  their  distance 
apart  and  the  region  of  the  body  on  which  they  are 
placed,  sometimes  two  sensations,  sometimes  one. 


THE  MECHANISM  OF  REASONING.          105 

Two  explanations  have  been  proposed.  The 
first,  simple  after  the  manner  of  all  a  priori  views, 
consists  in  saying  that  where  two  points  are  felt, 
each  of  them  has  separately  excited  a  nerve  fibre, 
and  that,  on  the  other  hand,  when  we  feel  only  a 
single  point,  the  points  of  the  compass  have  excited 
only  a  single  fibre.  In  every  case  we  experience  as 
many  sensations  as  there  have  been  nerves  excited. 
A  trace  of  this  explanation  remains  in  the  language, 
in  the  term  cercle  de  sensation.  If  one  of  the  two 
points  of  the  compasses  be  pressed  on  the  skin, 
and  if  it  be  tried  up  to  what  distance  from  the  first 
point  the  second  fails  to  produce  a  new  sensation, 
an  area  is  thus  circumscribed  which  has  the  form  of 
a  circle  or  of  an  ellipse.  This  area,  being  capable 
of  receiving  only  a  single  sensation,  corresponds, 
according  to  the  theory,  to  the  territory  of  one 
nerve  fibre ;  it  is  called  the  circle  of  sensation. 

This  explanation  contains  a  part  of  the  truth. 
There  is  no  doubt  that  the  portions  of  the  integu- 
ment whose  sensibility  is  very  delicate  are  richer  in 
corpuscles  of  touch  than  the  portions  whose  sensi- 
bility is  dull.  But  this  is  a  very  different  thing 
from  admitting  that  every  circle  of  sensation  is,  as 
has  been  said,  an  anatomical  unit,  the  territory  of  a 
single  fibre.  There  are  places  where  the  points  of 
the  compass  may  be  separated  by  more  than  a 
dozen  nerve  papillae  without  producing  any  more 
than  a  single  impression.  We  may  add  that  the 
limits  of  a  circle  of  sensation  vary  strikingly  under 
the  influence  of  attention  and  of  practice;  if  a  circle 
really  corresponded  to  the  province  of  a  single  fibre, 


Io6    THE  PSYCHOLOGY  OF  REASONING. 

this  would  be  an  invariable  unit.  Finally,  there  is 
a  more  conclusive  fact  than  all  the  others.  If  two 
circles  of  sensation,  whose  circumferences  are 
tangential,  are  drawn  upon  a  person's  forearm,  and 
if  one  of  the  points  of  the  compasses  be  placed  in 
one  circle  and  the  other  in  the  other,  the  two  being 
brought  as  near  together  as  possible,  the  person 
undergoing  the  experiment  will  experience  only 
one  sensation ;  in  order  to  produce  two,  the  points 
must  be  separated  by  the  whole  diameter  of  a 
circle.  If  it  were  true  that  each  circle  was  supplied 
by  a  special  fibre,  it  would  be  sufficient  for  the  two 
points  to  be  placed  upon  any  points  whatever  in 
the  two  circles  for  the  person  to  feel  both  of  them. 

The  second  explanation  is  known  under  the 
name  of  the  theory  of  nerve  fields.  It  is  observed 
that  for  two  sensations  of  touch  to  be  distinguished 
there  must  be  between  the  excited  points  on  the 
skin  a  certain  space,  a  certain  number  of  nerve 
ramifications,  a  nerve  field.  Only  this  distance  is 
necessary,  and  it  is  sufficient.  Why  is  it  so?  Be- 
cause, it  is  said,  two  things  can  only  be  distin- 
guished if  something  separates  them.  The  excita- 
tion of  the  two  nerve  fibres  can  only  produce  two 
distinct  impressions  if  these  two  fibres  are  separated 
by  unimpressed  nerve  elements.  These  elements, 
whose  role  is  to  divide  the  two  sensations,  are 
represented  by  the  distance  apart  of  the  two  points 
of  the  compass. 

This  pretended  explanation  seems  to  us  to  be 
simply  a  tautology ;  it  affirms  the  necessity  for  the 
separation  of  the  points,  which  is  a  fact  of  observa- 


THE  MECHANISM  OF  REASONING.          107 

tion ;  but  it  is  not  apparent  what  can  be  the  role  of 
the  intervening  nerve  fibres,  since  nothing  produces 
an  impression  upon  them.  The  theory  of  nerve 
fields  is  powerless  to  explain  this. 

The  explanation  which  I  propose  to  substitute 
for  the  preceding  ones  may  be  summed  up  in  a  few 
words.  I  assume  that  every  point  on  our  epidermis 
has  a  special  way  of  feeling ;  the  quality  of  the  sen- 
sation varies  with  the  region  of  the  skin ;  for  ex- 
ample, when  the  forehead,  then  the  cheek,  chin, 
neck  and  the  nape  of  the  neck  are  pressed  by  the 
finger,  a  different  tactile  sensation  is  produced  every 
time.  This  variation  always  takes  place  in  a  con- 
tinuous manner  from  one  point  to  another;  if  we 
chose  two  points  close  together  it  might  happen 
that  the  difference  between  the  two  sensations 
would  be  too  slight  to  be  perceived,  and  that  the 
two  sensations  would  behave  practically  as  if  they 
were  identical.  The  distance  at  which  the  two  sen- 
sations may  be  distinguished  in  consciousness  is  not 
uniform  over  the  whole  body,  for  the  local  quality 
of  each  sensation  does  not  vary  equally  all  over. 
This  being  admitted — and  we  shall  shortly  enumer- 
ate the  arguments  which  prove  our  hypothesis — 
what  will  happen?  By  exciting  two  points  on  the 
skin  with  the  compasses,  we  may  produce  at  pleas- 
ure, according  to  the  distance  apart  of  the  points 
and  the  region  of  the  skin,  two  different  sensations 
or  two  similar  sensations;  they  will  be  different 
when  the  points  on  the  skin  are  far  enough  apart 
for  their  difference  of  sensibility  to  be  appreciable; 
they  will  be  alike  when  the  points  selected  are  suf- 


loS    THE  PSTCHOLOGT  OF  REASONING. 

ficiently  near  to  each  other  for  their  sensibilities  to 
appear  the  same  in  kind. 

Now,  in  the  case  of  two  different  sensations,  the 
subject  will  feel  the  two  points  distinctly;  in  the 
case  of  two  similar  sensations,  these  sensations  will 
become  fused  into  one,  and  the  subject  will  feel 
only  one  point. 

Weber's  experiment  would  be  explained,  accord- 
ing to  this  hypothesis,  by  the  fusion  of  similar  sen- 
sations; it  would  be  an  illustration  of  the  law  of 
fusion.  But  what  must  be  added  to  demonstrate 
the  truth  of  this  hypothesis?  Two  things  must  be 
proved : 

First. — That  the  sensations  produced  by  the  two 
points  of  a  pair  of  compasses  are  of  different  quality 
when  the  subject  perceives  the  two  points. 

Second. — That  the  sensations  produced  by  the 
two  points  of  a  pair  of  compasses  are  of  the  same 
quality  when  the  subject  perceives  a  single  point. 

Lotze,  Wundt,  Helmholtz  and  others  in  Germany 
have  attributed  a  difference  of  sensibility  to  the 
different  regions  of  the  body.  This  is  what  is  called 
the  theory  of  local  signs.  We  shall  choose  one,  the 
most  striking,  from  among  the  proofs  of  this  theory : 
it  is  derived  from  the  phenomenon  of  localization. 
When  we  touch  a  person  on  any  part  whatever  of 
his  body,  he  feels  and  at  the  same  time  he  localizes 
the  excitation.  This  knowledge  of  place  is  not 
innate;  it  is  acquired.  It  is  formed,  in  all  prob- 
ability, in  the  following  manner:  We  have  learned 
by  experience  that  when  we  feel  a  certain  tactile 
sensation,  a  pressure  is  produced  on  the  arm ;  a 


THE  MECHANISM  OF  REASONING.          109 

certain  other  sensation  corresponds  with  an  action 
on  the  toe,  and  so  on.  In  the  course  of  time  we 
have  connected  a  definite  sensation  with  the  sight 
of  our  arm,  another  with  the  sight  of  our  toe,  and 
finally  each  different  sensation  with  the  sight  of  a 
different  point  on  our  skin.  When  we  come  to 
press,  prick  or  pinch  our  body,  the  sensation  proper 
to  the  part  affected  awakens  the  ocular  image  of 
that  part  by  the  mere  power  of  association.  It  is 
a  mental  law  that  when  two  sensations  have  been 
experienced  in  contiguity  they  adhere  in  such  a  way 
that  the  one  presented  suggests  the  other.  In  the 
present  case  the  suggestion  is  effected  so  rapidly 
that  the  visual  image  of  the  part  touched  follows 
the  tactile  sensation  immediately.  Localization  is 
nothing  else.  As  regards  the  position  of  the  point 
touched,  it  is  given  us  by  our  muscular  activity. 
This  explanation  of  the  genesis  of  the  sense  of  place 
always  assumes  one  thing:  that  two  sensations  of 
contact  which  are  referred  to  two  different  parts  of 
the  body  both  possess  a  local  sign  which  distin- 
guishes them  and  prevents  them  from  being  con- 
founded with  each  other.  Suppose  all  our  sensa- 
tions of  contact  were  absolutely  uniform.  A  per- 
son pricked  on  the  finger  will  not  know  whether  it 
was  on  his  finger  or  his  toe,  for  if  his  toe  had  been 
pricked  he  would  have  experienced  the  same  sen- 
sation. For  one  sensation  of  contact  to  become 
associated  with  the  sight  of  the  finger,  and  another 
with  the  sight  of  the  toe,  it  is  absolutely  necessary 
that  the  two  sensations  be  different ;  otherwise  they 
will  be  confounded  with  each  other,  and  the  sensa- 


I  io    THE  PSTCHOLOGT  OF  REASONING. 

tion  whose  seat  is  at  the  finger  will  be  able  to  sug- 
gest indifferently  the  ocular  image  of  quite  another 
part  of  the  body. 

In  short,  localization  implies  distinct  sensations. 
This  fact  puts  us  in  a  position  to  know  when  the 
two  sensations  produced  by  the  compasses  are  sim- 
ilar or  different.  Are  they  susceptible  to  being 
localized  in  a  distinct  manner?  Then  they  are 
different.  Are  they  not  susceptible  of  distinct 
localization?  Then  they  are  similar. 

By  making  use  of  this  criterion,  we  find  that  in 
every  case  in  which  the  two  sensations  are  felt 
double  the  subject  can  localize  them,  which  proves 
that  they  are  of  different  natures.  For  example,  I 
press  the  two  points  of  my  compasses  transversely 
on  a  person's  forearm,  the  points  being  thirty-nine 
lines  apart,  the  distance  necessary  for  the  subject 
to  feel  each  point  separately.  Then  I  lift  the  two 
points  up  alternately,  asking  the  person,  whose 
eyes  are  shut,  to  inform  me  if  it  is  the  right  or  the 
left  one  he  continues  to  feel.  He  replies  correctly 
every  time;  he  localizes  exactly.  This  is  plain 
proof  that  each  of  these  sensations  differs  a  little 
from  the  other.  Thus  in  the  case  where  the  sub- 
ject perceives  two  points,  there  are  two  different 
sensations,  as  is  proved  by  the  possibility  of  distinct 
localization. 

Conversely,  we  have  to  investigate  if  it  is  pos- 
sible for  the  subject  to  give  a  different  localization 
to  two  sensations  which,  simultaneously  produced, 
have  the  effect  of  a  single  sensation.  We  try 
experimentally  how  far  apart  we  may  put  the  two 


THE  MECHANISM  OF  REASONING.         1 1 1 

points  without  their  ceasing  to  be  confounded  with 
each  other,  and  we  mark  with  ink  the  points  on 
the  epidermis  at  which  they  are  placed.  It  is 
always  well  not  to  go  as  far  as  the  maximum  dis- 
tance, for  it  varies  a  little  during  the  course  of  the 
investigation,  merely  by  attention  and  exercise;  it 
might  therefore  happen  with  the  maximum  dis- 
tance that  the  two  sensations,  which  were  at  first 
similar,  became  in  a  moment  different,  a  condition 
of  things  which  would  disturb  the  experiment. 
After  these  preparations,  we  excite  alternately  the 
two  points  marked  with  ink,  asking  the  subject  to 
state,  with  his  eyes  shut,  upon  which  one  the 
instrument  is  placed.  The  subject  does  not  succeed 
in  this,  or,  if  he  tries  to  localize,  he  does  so  with 
alternate  success  and  failure,  which  proves  that  he 
is  guessing.  This  inability  to  localize  the  two  sen- 
sations can  depend  upon  only  one  cause,  the  sim- 
ilarity of  the  two  sensations. 

It  is  therefore  true  that  the  experiment  with  the 
compasses  gives  us  an  example  of  the  fusion  of  two 
similar  sensations.  This  is  all  that  we  wished  to 
show.* 

In  the  preceding  experiment  the  sensations 
which  are  fused  together  are  exactly,  or  almost 
exactly,  alike,  and  the  fusion  resulting  from  their 
being  brought  together  is  total.  Let  us  give  an 
example  of  partial  fusion.  A  partial  fusion  often 
exists  in  a  series  of  sensations  which  succeed  one 
another,  and  each  of  which  resembles,  in  part  only, 

*For  further  details  I  may  refer  to  my  article  on  the  Fusion  des  sensa- 
tions semblables  {Revue  philosophique,  September,  1880). 


112         THE  PSYCHOLOGY  OF  REASONING. 

that  which  precedes  and  that  which  follows  it. 
This  is  what  occurs  in  the  zootrope,  thaumatrope, 
phenakistoscope,  dedaleum,  cinematograph,  etc. 
These  scientific  toys  are  designed  to  produce  a 
series  of  impressions  on  the  retina  of  the  observer, 
representing  the  successive  phases  of  any  periodic 
movement,  for  example,  a  man  who  juggles  with 
his  head. 

Each  figure  in  the  zootrope,  taken  separately, 
differs  very  little  from  its  neighbour  on  the  right 
and  on  the  left;  their  resemblance  may  be  ex- 
pressed by  the  following  letters  abc,  bed,  cde,  def, 
efg,  fgh,  etc.,  which  indicate  the  portion  common 
to  two  successive  impressions.  When  the  toy  is 
put  in  motion  and  its  rotation  is  sufficiently  rapid, 
the  impressions  become  fused  together  by  their 
common  points  and  give  us  the  illusion  of  a  single 
person,  always  the  same,  who  makes  the  move- 
ments. 

The  study  of  the  mechanism  of  this  illusion  is 
the  more  interesting  because  it  artificially  repro- 
duces what  occurs  every  time  that  we  perceive  a 
body  undergoing  changes  of  form  or  position,  for 
example,  a  trotting  horse.* 

We  prefer  to  collect  facts  rather  than  linger 
over  explanations  which  will  come  of  their  own 
accord.  Let  us  confine  ourselves  to  anticipating 
a  possible  objection  by  showing  that  the  fusion  of 
zootropic  images  is  effected  in  the  brain  and  not,  as 
one  might  believe,  in  the  retina.  This  is  proved, 
first  of  all,  by  the  fact  that  the  consecutive  visual 

*Clittord  has,  by  extending  the  idea  of  the  zootrope,  denied  that  the 
world  can  be  continuous. 


THE  MECHANISM  OF  REASONING.         113 

images  which  are  produced  in  this  fusion  have  a 
cerebral  seat  (see  above,  page  44).  In  the  second 
place,  there  is  the  more  direct  proof  that  the  fusion 
is  not  produced  en  bloc,  but  only  between  the  sim- 
ilar portions  of  the  images,  which  implies  a  power 
of  analysis  which  is  certainly  wanting  in  the  retina. 
The  fusion  of  similar  images.  —  Images  fuse 
together  like  sensations,  a  fact  which  is  understood 
once  their  nature  is  known,  for  they  are  revived 
sensations.  It  often  happens  that  a  succession  of 
images,  partially  similar,  passes  across  the  field  of 
the  mind,  producing  appearances  of  transformation 
comparable  to  those  of  the  zootrope.  One  of  Mr. 
Galton's  correspondents,  the  Rev.  George  Henslow, 
sees,  every  time  he  shuts  his  eyes  and  waits  a  short 
time,  the  clear  image  of  some  object.  This  object 
changes  its  form  for  as  long  as  Mr.  Henslow 
watches  it.  It  is  noticed,  in  studying  the  series  of 
successive  forms,  that  the  passage  from  one  to  the 
other  is  supplied  sometimes  by  relations  of  con- 
tiguity and  sometimes  by  relations  of  resemblance. 
In  one  of  these  experiments  the  following  images 
were  seen:  A  cross-bow,  an  arrow,  a  person 
shooting  the  arrow,  his  hands  alone  being  visible ;  a 
flight  of  arrows  completely  occupying  the  field  of 
vision;  falling  stars;  large  flakes  of  snow;  aland- 
scape  covered  with  a  sheet  of  snow;  a  rectory 
with  its  walls  and  roof  covered  with  snow;  a  spring 
morning,  with  a  brilliant  sun,  and  a  bed  of  tulips; 
the  disappearance  of  all  the  tulips  with  the  excep- 
tion of  one;  the  single  tulip  becomes  double;  its 
petals  fall  off  rapidly,  there  is  nothing  left  but  the 


114         THE  PSrCHOLOGT  OF  REASONING. 

pistil;  the  pistil  enlarges,  and  the  stigmata  change 
into  three  branching  brown  horns;  a  knob;  the 
knob  bends  and  becomes  a  stick;  then  a  sort  of 
pin  passing  through  a  metal  plate,  and  so  on. 
The  experimenter  has  sometimes  succeeded  in  com- 
pleting what  he  calls  a  "visual  cycle" — that  is  to 
say,  returning  to  the  original  image  and  going 
through  the  same  series  of  forms  anew.  These 
visions  recall  that  of  Goethe,  in  whose  case  the 
cycle  was  shorter.  "When  I  closed  my  eyes  and 
depressed  my  head,"  relates  the  German  poet,  "I 
could  cause  the  image  of  a  flower  to  appear  in  the 
middle  of  the  field  of  vision ;  this  flower  did  not 
for  a  moment  retain  its  first  form,  but  unfolded 
itself  and  developed  from  its  interior  new  flowers, 
formed  of  coloured  or  sometimes  green  leaves. 
These  flowers  were  not  natural  flowers,  but  of  fan- 
tastic forms,  although  symmetrical  as  the  rosettes 
of  sculptors.  I  was  unable  to  fix  any  one  form, 
but  the  development  of  new  flowers  continued  as 
long  as  I  desired  it,  without  any  variation  in  the 
rapidity  of  the  changes." 

It  is  plain  that  the  transformation  of  the  imag- 
inary object  is  produced  by  a  succession  of  images. 
But  it  is  important  that  the  nature  of  this  succession 
should  be  clearly  understood.  The  images  are  not 
simply  substituted  one  for  another,  the  last  to 
arrive  expelling  the  preceding  one ;  if  things  occurred 
thus,  we  would  have  distinct  images  replacing  each 
other,  and  not  a  single  image  which  is  metamor- 
phosed. It  must  be  understood  that  each  of  the 
images  is  fused  with  the  preceding  one  by  virtue  of 


THE  MECHANISM  OF  REASONING.         115 

the  common  points  which  they  offer,  and  that, 
besides,  the  two  successive  images  co-exist  during  a 
very  short  instant.  Thanks  to  these  two  condi- 
tions, the  two  images  form  a  whole  and  give  the 
appearance  of  a  single  image  undergoing  modifica- 
tion. 

The  hallucinations  of  the  insane  often  present 
the  same  evolution  of  forms.  Magnan  relates  that 
an  alcoholic  inebriate  saw  upon  the  wall  cobwebs, 
ropes,  nets  with  contracting  meshes ;  in  the  middle 
of  these  meshes  and  strands,  black  balls  appeared, 
which  enlarged,  became  smaller,  took  the  form  of 
rats,  cats,  passed  across  the  strands,  leaped  upon 
the  bed  and  disappeared.*  In  rarer  cases  the 
metamorphosis  requires  years.  A  young  girl  who 
had  become  insane  in  consequence  of  an  attempt  to 
assassinate  her,  continually  saw  the  fist  and  the  arm 
of  the  individual  who  had  attempted  to  kill  her. 
Now,  the  disease  following  its  course,  the  hallu- 
cination underwent  a  curious  transformation.  The 
image  which  was  seen  by  the  young  girl  became 
modified  thus:  Two  eyes  appeared  on  the  fist  of 
the  assassin,  his  arm  became  excessively  long,  and 
finally  the  hallucinatory  image  changed  into  a 
serpent. \  In  other  cases  the  outline  of  the  hallu- 
cination remains  constant,  but  the  dimensions 
change.  In  an  old  observation  by  Beyle,  a  patient 
saw  an  ordinary  cobweb,  which  grew  to  the  point 
of  filling  the  whole  of  his  room  and  suffocating 
him.  Dreams  supply  innumerable  examples  of 

*Magnan,  De  Falcoolisme,  p.  $6. 

fMax  Simon,  Le  monde  des  reves,  p.  118. 


Il6    THE  PSYCHOLOGY  OF  REASONING. 

these  kinds  of  transformation ;  sometimes  two  dis- 
tinct persons  are  seen  blending  into  one;  or  the 
same  person  changes  his  physical  personality,  etc. 
The  dream  is  the  true  type  of  metamorphic  hallu- 
cinations.* 

We  mention  these  morbid  cases  because  the 
phenomenon  which  we  are  studying  is  therein 
magnified  and  more  easily  examined.  But  we  also 
meet  excellent  examples  of  the  fusion  of  images  in 
the  normal  operations  of  life.  According  to  Hux- 
ley, the  formation  of  general  ideas  would  be 
effected  by  the  union,  the  fusion,  the  coalescence 
of  several  images  of  individual  objects ;  and  in  order 
to  express  his  thought  better,  the  naturalist-philos- 
opher makes  use  of  an  ingenious  comparison,  drawn 
from  the  Composite  Portraits  which  we  owe  to  Mr. 
Francis  Galton's  invention. f  "This  mental  opera- 
tion may  be  rendered  comprehensible,"  says  Huxley, 
speaking  of  the  generalization  of  an  image,  "by  con- 
sidering what  takes  place  in  the  formation  of  com- 
pound photographs — when  the  images  of  the  faces  of 
six  sitters,  for  example,  are  each  received  on  the  same 
photographic  plate,  for  a  sixth  of  the  time  requisite 
to  take  one  portrait.  The  final  result  is  that  all 
those  points  in  which  the  six  faces  agree  are  brought 
out  strongly,  while  all  those  in  which  they  differ 
are  left  vague;  and  thus  what  may  be  termed  a 
generic  portrait  of  the  six,  in  contradistinction  to  a 

*J.  Sully,  op.  fit.,  p.  163;  and  Maury,  Sommeil  et  reves,  p.  146.  M. 
Delboeuf  has  compared  the  metamorphoses  in  dreams  to  dissolving'  views : 
"  It  is,"  he  says,  "  as  if  we  projected  two  pictures  on  the  same  screen,  and  at 
the  same  place,  by  means  of  two  magic  lanterns,  and  illuminated  one  while 
the  other  was  being  extinguished."  (Revue  f  kilos.,  June,  1880).  This  ex- 
planation confirms  ours,  it  does  not  destroy  it. 

tGalton,  Inquiries  into  Human  Faculty  and  its  Development  (Ap- 
pendix: Generic  Images). 


THE  MECHANISM  OF  REASONING.          117 

specific  portrait  of  any  one,  is  produced.*  This 
beautiful  invention  has,  it  appears,  already  pro- 
duced brilliant  results.  By  combining  in  a  single 
photograph  five  medals  representing  Cleopatra, 
which,  far  from  giving  an  idea  of  the  beauty  of  that 
celebrated  queen,  had  a  hideous  appearance,  a 
much  more  pleasant  composite  portrait  was  obtained. 
It  is  probable  that  the  points  of  resemblance  be- 
tween the  different  likenesses  were  reinforced  in 
this  resultant,  and  that  the  points  of  difference 
remained  unaccentuated  (jlous);  so  that  we  may 
reasonably  maintain  that  the  composite  portrait  has 
a  better  chance  of  being  like  the  model  than  its 
components.  Photographs  of  individuals  belonging 
to  the  same  classes  have  also  been  combined  by  this 
method,  and  thus  certain  types,  as  for  example, 
the  swindler  type,  have  been  obtained.  This 
method  will  perhaps  become  useful  to  criminal 
anthropology  in  the  future. 

Huxley's  comparison  between  these  composite 
photographs  and  concepts  has  been  accepted  by 
many  psychologists;  it  has  been  regarded  as  very 
probable  that  the  generalization  of  an  image  is 
formed  in  the  mind  like  the  generic  photograph  on 
the  sensitive  plate,  by  the  superposition  of  particu- 
lar impressions.  We  may  add  a  corroborative 
argument.  M.  Pouchet  has  remarked  that  the  con- 
secutive images  of  his  microscopic  preparations 
which,  as  we  have  already  seen,  sometimes  ap- 
peared to  him  after  a  long  interval,  do  not  represent 
any  preparation  in  particular,  but  are  like  the  mean 

*Hux!ey,  Hume  (English  Men  of  Letters  Series},  p.  95. 


IlS         THE  PSYCHOLOGT  OF  REASONING. 

of  a  series  of  preparations  of  the  same  kind.  This 
fact  tends  to  show  that  the  generic  image  is  the 
result  of  the  coalescence  of  several  particular  im- 
pressions united  into  a  single  one. 

However,  it  would  be  very  unscientific  to 
explain  a  mental  operation  by  a  comparison  with  a 
purely  mechanical  phenomenon,  unless  that  com- 
parison implicitly  assumed  the  existence  of  a  prin- 
ciple of  fusion.  The  formation  of  generic  images  is 
explained  by  the  principle  of  fusion;  particular 
impressions,  becoming  fused  together,  form  a 
generic  image  because  their  common  parts  are  fused 
together  and  are  brought  out  strongly,  while  the 
parts  which  differ  remain  separate  and  become 
vague. 

The  comparison  between  the  generic  image  and 
the  composite  photograph  is  only  accurate  in  so  far 
as  it  illustrates  this  mental  law ;  taken  literally,  it 
is  not  rigorously  exact.  If  the  eye  of  a  man,  says 
Galton,  be  put  in  the  place  of  the  object  glass  of 
the  apparatus  used  in  obtaining  composite  portraits, 
the  image  which  would  be  formed  in  his  brain  would 
not  be  identical  with  the  composite  portrait.  For, 
contrarily  to  the  photographic  effect,  the  physiolo- 
gical effect  of  an  impression  is  not  proportional  to 
its  duration  or  its  frequency;  we  know  that,  accord- 
ing to  Weber's  law  (a  disputable  law,  whose  fault  is 
that  it  is  too  precise),  the  sensation  varies  as  the 
logarithm  of  the  stimulus;  in  order  that  the  sensa- 
tion may  follow  an  arithmetical  progression,  the 
stimulus  must  follow  a  geometrical  progression. 
We  may  also  add  the  disturbing  effect  of  attention, 


THE  MECHANISM  OF  REASONING.          Up 

of  emotion,  of  preconceived  ideas,  and  of  a  great 
number  of  other  factors,  which  prevent  the  mind 
from  fusing  several  images  together  with  the  exact- 
ness of  a  photographic  plate. 

We  have  given  a  sufficient  number  of  examples 
to  make  it  clearly  understood  in  what  the  fusion 
of  sensations  and  of  images  consists.  It  seems 
impossible  that  a  phenomenon  so  easy  of  observation 
should  have  passed  unnoticed.  Among  the  authors 
who  have  alluded  to  it  we  may  first  of  all  mention 
Herbert  Spencer.  Defining  a  state  of  conscious- 
ness, this  author  says  that  it  is  "any  portion  of 
consciousness  which  occupies  a  place  sufficiently 
large  to  give  it  a  perceivable  idividuality ;  which  has 
its  individuality  marked  off  from  adjacent  portions 
of  consciousness  by  qualitative  contrasts,  and  which, 
when  introspectively  contemplated,  appears  to  be 
homogeneous.'"*  It  follows  from  this  definition  that 
if  the  portions  adjacent  to  the  state  considered  are 
not  different,  they  form  part  of  the  same  state; 
but  to  say  that  is  to  implicitly  recognize  the  prin- 
ciple of  fusion.  Later  on  Mr.  Spencer  adds: 
"The  requisite  to  the  existence  of  two  feelings  is 
some  difference."^  Therefore,  if  there  is  no  differ- 
ence, there  is  a  single  state,  that  is  to  say  a  fusion 
of  the  two  states  into  one.  These  few  quotations 
show  us  that  Mr.  Spencer  has  observed,  at  least  in 
passing,  the  phenomenon  of  fusion,  but  without 
comprehending  its  importance. 

Mr.  Bain  has  made  a  few  remarks  on  the  same 
phenomenon.  "In  the  case  of  perfect  identity 

*Spencer,  Principles  of  Psychology,  Vol.  I,  p.  164. 
\Op.  cit.,  Vol.  I.  p.  167. 


120    THE  PSTCHOLOGT  OF  REASONING. 

between  a  present  and  a  past  impression,  the  past 
is  recovered  and  fused  with  the  present,  instantane- 
ously and  surely.  So  quick  and  unfaltering  is  the 
process  that  we  lose  sight  of  it  altogether;  we  are 
scarcely  made  aware  of  the  existence  of  an  associat- 
ing link  of  similarity  in  the  chain  of  sequence. 
When  I  look  at  the  full  moon,  I  am  instantly  im- 
pressed with  the  state  arising  from  all  my  former 
impressions  of  her  disc  added  together."*  The 
description  refers  to  a  case  which  we  shall  consider 
presently :  the  fusion  of  a  sensation  with  an  image. 
Elsewhere  the  same  author  speaks  of  cases  in  which 
we  are  cognizant  of  an  identity  without  being 
able  to  say  what  the  identical  thing  is,  as  for 
example  when  a  portrait  gives  us  the  impression 
that  we  have  seen  the  original,  without  our  being 
capable  of  saying  what  the  original  is.  The  iden- 
tity has  struck  our  mind,  but  the  restoration  is  not 
made.  Everybody  knows  that  very  singular  feel- 
ing of  "already  seen."  Mr.  Bain  explains  it  by 
the  absence  of  recollection  of  the  different  parts  of 
the  object  identified.  In  fact,  in  order  that  the 
mind  may  perceive  the  resemblance  between  two 
images,  they  must  differ  a  little;  if  they  do  not, 
they  become  added  together  and  form  a  single 
image.  Lotze  expresses  the  same  idea  with  a 
lourdeur  which  is  quite  German:  "We  should 
know  nothing  whatever  of  this  fact,  the  reproduc- 
tion of  a  former  a  by  the  present  A,  if  the  two 
were  simply  present,  with  no  distinction  between 
them,  at  the  same  time.  To  know  the  present  A 

*Bain,  The  Senses  and  the  Intellect,  p.  466. 


THE  MECHANISM  OF  REASONING.    121 

as  repetition  of  the  former  a,  we  must  be  able  to 
distinguish  the  two;  and  we  do  this  because  not 
only  does  the  repeated  A  bring  with  it  the  former 
one  which  is  its  precise  counterpart,  but  this  former 
one  also  brings  with  it  the  ideas  c  d,  which  are 
associated  with  it  but  not  with  the  present  A,  and 
thereby  testifies  that  it  has  been  an  object  of  our 
perception  on  some  former  occasion,  but  under 
different  circumstances."* 

This  fusion  has  also  been  described  by  Wundt 
under  the  names  of  assimilation  and  simultaneous 
association.  "The  perception  which  results  from 
the  actual  excitation  of  any  one  of  the  senses  com- 
bines with  a  representation  reproduced  by  mem- 
ory." Finally,  it  is  only  right  to  recall  that 
Ampere  had,  long  before  Wundt,  described  and 
analyzed  the  phenomenon,  which  he  called  concre- 
tion. It  was  Ampere,  M.  Pilon  tells  us  in  a  lumin- 
ous article  on  the  Formation  des  idtes  abstraites  et 
ge'ne'rales^  it  was  Ampere  who  first  showed  that  the 
images  of  former  sensations  modify  our  actual  sen- 
sations to  the  point  of  making  us  see  more  than  we 
see,  and  hear  more  than  we  hear.  A  man  speaks 
to  us  in  a  language  which  is  quite  unknown  to  us; 
why  do  we  not  distinguish  what  he  utters,  while  if 
he  speaks  in  a  familiar  language,  we  clearly  per- 
ceive every  word  he  pronounces?  It  is,  replied 
Ampere,  by  reason  of  the  concretion  which  takes 
place  between  the  present  sensations  of  sounds  and 
the  images  of  those  same  sounds  which  we  have 

*Metaphysik,  Book  III,  Ch.  II. 

\Critique philosophique.  Vol.  I,  No.  3.    (New  series.) 


122         THE   PSYCHOLOGY  OF  REASONING. 

often  heard.  "If  the  words  which  are  sung  in  the 
Italian  opera,"  he  said  again,  "are  not  pronounced 
strongly,  the  listener  seated  at  the  back  of  the  the- 
atre receives  the  impression  of  vowels  and  musical 
modulations  only;  but  he  does  not  hear,  and  there- 
fore does  not  recognize,  the  words  pronounced.  If 
he  then  opens  the  book  of  words  of  the  opera,  he 
will,  by  following  them  with  his  eyes,  hear  quite 
distinctly  these  same  utterances  which  he  was 
unable  to  catch  a  moment  before.  What  has  hap- 
pened to  him  is  this.  The  sight  of  the  characters 
before  his  eyes,  forming  not  only  the  visual  sensa- 
tion of  the  moment,  but  images  of  sensations  of  the 
same  kind  which  he  has  experienced  in  learning  to 
read  Italian,  the  sight  of  the  written  words  awakens 
in  him  the  sonorous  and  acoustic  images  of  the 
words  pronounced,  and  the  images  of  the  sounds 
reinforcing  in  his  mind  the  too  feeble  impressions 
received  from  the  stage,  the  result  is  that  he  hears 
distinctly."* 

Here  our  quotations  cease.  They  suffice  to 
show  that  our  study  of  the  fusion  of  similar  states 
of  consciousness  is  altogether  without  originality, 
for  this  phenomenon  has  been  perceived  by  a  num- 
ber of  authors. 

While  not  wishing  to  exhaust  this  subject,  we 
desire  to  say  a  few  words  on  its  physiological 
aspect.  We  have  this  moment  seen  the  role  re- 
semblance plays  in  the  sphere  of  sensations  and 
images:  it  suggests  and  fuses.  The  first  effect  is 
better  known  than  the  second.  However,  we 

*Philosophie  des  deux  Ampere,  p.  37. 


THE  MECHANISM  OF  REASONING.          123 

believe  that  we  have  placed  the  fusion  of  similar 
sensations  and  also  of  similar  images  beyond  doubt. 
We  even  infer,  by  means  of  induction,  that  this 
phenomenon  occurs  every  time  that  we  perceive  a 
resemblance,  from  the  insignificant  act  which  makes 
us  recognize  a  friend,  to  the  flash  of  genius  which 
discerns  an  identity  between  the  most  remote  phe- 
nomena, such  as  the  fall  of  a  stone  and  the  force 
which  urges  the  moon  towards  our  globe. 

It  remains  to  discover  whether  there  exists  a 
physiological  phenomenon  which  might  be  consid- 
ered as  the  basis  of  this  double  property  of  resem- 
blance. 

We  may  assume  as  exceedingly  probable  that 
two  states  of  consciousness  which  resemble  each 
other  totally  or  in  part,  must  in  general  involve  the 
entering  into  activity  of  the  same  nerve  elements, 
cells  and  fibres,  totally  or  in  part — that  is  to  say,  to 
the  same  degree.  This  hypothesis  appears  to.  us 
to  be  a  necessary  consequence  of  the  principle  of 
cerebral  localizations,  according  to  which  all  im- 
pressions of  the  same  kind  affect  the  same  part  of 
the  brain.  But  it  is  by  no  means  necessary  that 
the  rule  should  be  made  absolute ;  we  are  inclined 
to  admit  that  there  exist  in  the  brain  non-differen- 
tiated territories,  where  even  similar  impressions 
may  affect  distinct  points.  After  having  made  this 
restriction  in  our  hypothesis,  we  may  mention  some 
of  the  numerous  facts  which  militate  in  its  favour. 

We  all  know  the  involuntary  mistakes  which 
make  us  pronounce  one  word  instead  of  another. 
Lewes  records  that  he  was  one  day  relating  a  visit 


124         THE  PSYCHOLOGY  OF  REASONING. 

to  the  epileptic  hospital,  and,  intending  to  name 
the  friend,  Dr.  Bastian,  who  accompanied  him,  he 
said,  "Dr.  Brinton,"  then  immediately  corrected 
this  with  "Dr.  Bridges;"  this  also  was  rejected, 
and  Dr.  Bastian  was  pronounced.  "I  was,"  he 
says,  "under  no  confusion  whatever  as  to  the  per- 
sons, but,  having  imperfectly  adjusted  the  group 
of  muscles  necessary  for  the  articulation  of  the  one 
name,  the  one  element  which  was  common  to  that 
group  and  to  the  others,  namely  B,  served  to  recall 
all  three."  M.  Ribot,  from  whom  we  borrow  the 
preceding  quotation,*  has  made  an  analogous  obser- 
vation on  mistakes  in  writing.  Wishing  to  write 
"doit  de  bonnes,"  he  wrote  "donne;"  wishing  to 
write  "ne  pas  faire  une  part,"  he  wrote  "ne part 
faire."  We  may  again  remark  that  in  patholog- 
ical paraphrasias  and  paragraphias  the  confusion  is 
often  produced  also  by  an  identity  of  letters  or  by 
consonance. 

All  this  is  explained,  as  the  authors  just  quoted 
observe,  by  supposing  that  the  same  nerve  elements 
enter  into  different  combinations,  and  that  for 
example  the  names  of  Bastian,  Bridges  and  Brinton 
correspond  to  complexus  of  cells  which  have  a  com- 
mon element,  the  element  which  corresponds  to  B. 
Thus  the  psychical  quality  of  the  resemblance  would 
find  its  anatomical  counterpart  in  an  identity  of  seat. 

A  phenomenon  analogous  to  paraphrasia  may 
be  produced  in  oneself  at  will  by  setting  one- 
self the  problem  of  finding  a  proper  name  which 
one  knows  but  which  is  not  before  the  mind  at  the 

Diseases  of  Memory,  p.  29.    (Appleton,  N.  Y.) 


THE  MECHANISM  OF  REASONING.          125 

time.  Experimental  psychology  may  thus  be  studied 
without  a  laboratory.  One  day  I  tried  to  recall 
to  mind  the  name  of  one  of  my  friends  to  whom  I 
wished  to  write  a  letter;  this  friend  is  called 
M.  Truchy.  I  did  not  succeed  in  finding  his  name 
again  immediately.  I  passed  through  the  follow- 
ing intermediate  steps,  which  I  noted  down  accord- 
ingly, for  they  afford  a  beautiful  example  of  para- 
ph rasia  : 

Mony 

Mouc/iy 

Suchy 


Truchy 

At  each  effort  of  memory  I  gained  one  or  two 
correct  letters.  The  course  of  the  experiment 
seems  to  show  clearly  that  the  letters  common  to 
the  series  of  names  involve  the  excitation  of  the 
same  nerve  elements.* 

We  may  therefore  accept  as  a  very  likely  hypothe- 
sis that  the  resemblance  between  two  states  of  con- 
sciousness generally  has  its  physiological  counter- 
part in  an  identity  of  seat  of  the  nerve  process. 
This  hypothesis  has  moreover  been  already  pointed 
out  by  Mr.  Spencer.  Every  image,  he  says,  tends 
to  aggregate  with  like  images  by  virtue  of  the  iden- 
tity of  their  cerebral  seat. 

We  may  now  make  our  deductions.  First  of 
all,  it  becomes  possible  to  explain  the  suggestive 
action  of  resemblance  physiologically.  That  every 

*Many  other  proofs  might  be  mentioned.  For  example,  repetition 
strengthens  the  association  of  two  images,  or  of  two  movements;  how  could 
that  be  explained  without  admitting  that  the  same  nerve  elements  receive 
impressions  at  every  repetition?  etc. 


126         THE  PSTCHOLOGT  OF  REASONING. 

state  of  consciousness  has  the  property  of  reviving 
those  similar  to  it,  is  due  to  the  complexus  of  cells 
which  correspond  to  the  excitative  state  and  to  the 
state  excited  having  common  points,  by  which  the 
nerve  wave  flows  away  from  the  first  group  of  cells 
into  the  second.  It  is  equally  easy  to  understand 
the  fusion  of  two  similar  states  into  one,  since 
they  have  a  numerically  single  nerve  element  as 
their  basis. 

This  hypothesis  has  a  second  advantage;  it 
explains  how  a  resemblance  between  ideas  is  effect- 
ual even  when  it  is  not  recognized  by  the  mind. 

Psychologists  are  asked  what  may  be  properly 
understood  by  a  resemblance  which  would  not  be 
perceived.  Resemblance,  it  has  been  said,  implies 
a  mental  comparison,  and  when  this  comparison  is 
absent,  when  there  is  no  consciousness,  the  resem- 
blance can  no  longer  exist  (Penjon).  The  true 
solution  of  the  difficulty  seems  to  us  to  be  as  follows: 
It  is  true  that  there  is  no  resemblance  without  the 
consciousness  of  the  resemblance,  for  the  two  things 
are  in  reality  only  one.  But  consciousness  is  only 
an  epiphenomenon,  superadded  to  cerebral  activity, 
and  capable  of  disappearing  without  the  corre- 
sponding nerve  process  being  altered.  Two  similar 
images  succeed  each  other  in  our  mind.  It  matters 
little  whether  we  did  or  did  not  notice  their  resem- 
blance, for,  being  similar,  they  will  put  a  common 
cell  element  in  vibration.  This  identity  of  seat  will 
be  sufficient  to  produce  all  the  results  which  are 
produced  by  a  resemblance  which  is  recognized  and 
judged  by  a  conscious  comparison. 


THE  MECHANISM  OF  REASONING.         127 

Thus  it  happens  that  an  image  suggests  one  sim- 
ilar to  it,  without  consciousness  participating  in  the 
act.  Is  it  not,  moreover,  in  this  way  that  sugges- 
tion by  resemblance  operates?  Like  automatically 
evokes  like;  when  the  act  is  accomplished,  reflexion 
intervenes  to  give  an  account  of  what  has  happened, 
and  it  is  only  then  that  we  discover  the  existence  of 
a  resemblance  in  the  chain  of  ideas.  M.  Pilon  has 
developed  the  same  idea  with  his  usual  lucidity. 
"We  must  distinguish,"  he  says,  "between  associa- 
tion by  resemblance  and  the  perception  of  the 
resemblance.  It  is  not  by  means  of  the  relation  of 
resemblance  perceived  between  two  ideas  that  one  of 
these  ideas  may  suggest  the  other;  for  this  percep- 
tion of  resemblance  implies  that  the  two  ideas  are 
present  to  the  mind,  and  consequently  that  the 
association  is  already  formed.  To  say  that  resem- 
blance is  an  element  in  association  is  simply  to  say 
that  one  idea  has  the  property  of  suggesting  another 
idea  which  the  mind  then  recognizes,  by  means  of 
the  faculty  of  perceiving  relations,  as  similar  to  the 
first."  (Op.  cit.,  p.  194.) 

Another  deduction  of  the  same  kind  as  the  pre- 
ceding one  is  that  the  formation  of  general  ideas 
must  take  place  without  the  intervention  of  the 
self,  in  the  same  manner  as  suggestion  by  similar- 
ity and  for  the  same  reasons,  by  the  sole  virtue  of 
the  images  raised ;  or,  in  more  accurate  terms,  by 
the  effect  of  the  identity  of  seat  of  the  particular 
impressions.  Images  have  the  property  of  organ- 
izing themselves  into  general  images,  as  they  have 
the  property  of  suggesting  similar  images.  Thus 


128    THE  PSrCHOLOGT  OF  REASONING. 

we  possess  general  ideas  which  are  produced  in  us 
entirely  by  themselves,  such  as  the  general  idea  of 
a  chair,  a  knife,  etc. 

It  will  perhaps  be  thought  that  these  views  of 
cerebral  physiology,  although  they  may  be  hypo- 
thetical, have  the  advantage  of  according  with  the 
prepossession  of  many  psychologists  who  seek  the 
explanation  of  mental  operations  in  the  properties 
of  the  nervous  system.  Here  we  have  the  oppor- 
tunity of  showing  what  this  prevalent  opinion  is 
worth,  it  being  more  correct  in  appearance  than  in 
reality.  Let  us  admit,  for  an  instant,  that  it  is  not 
merely  probable,  but  absolutely  demonstrated 
that  two  similar  states  of  consciousness  have  a 
single  nerve  element  in  the  brain  as  their  basis,  and 
that  this  unity  of  seat  explains  the  two  effects  of 
resemblance :  suggestion  and  fusion.  Does  any  one 
by  chance  believe  that  we  have  here,  in  the  proper- 
ties of  the  nervous  system,  a  true  explanation  of  the 
properties  of  resemblance?  That  would  be  a  singu- 
lar illusion.  For  this  is  no  explanation  whatever, 
but  simply  a  transposition  into  physiological  terms 
of  the  phenomenon  which  is  claimed  as  explained. 
What  is  this  single  element  which  we  state  to  be  the 
basis  of  resemblance?  How  can  we  understand  its 
unity  if  we  have  not  the  idea  of  number,  of  plurality, 
and  is  this  idea  not  at  least  more  complex  than 
that  of  resemblance?  "Nous  voilh  au  rouet,"  as 
Montaigne  said. 

The  truth  is  that  we  can  only  know  exterior 
things  by  referring  them  to  the  laws  of  our  mind, 
and  that  consequently  the  study  of  one  of  these 


THE  MECHANISM  OF  REASONING.          129 

objects,  a  brain  for  example,  can  give  us  no  infor- 
mation as  to  the  forms  of  our  thought,  for  it  always 
implies  them.  Those  who  maintain  the  contrary 
are  guilty  of  a.  petitio  principii.* 

II. 

Thus  extended  and  modified,  the  law  of  resem- 
blance will  enable  us  to  understand  the  genesis  of 
external  perception.  Let  us  study  this  genesis  in 
itself,  without  any  preconceived  ideas,  without 
considering  that  the  phenomenon  is  a  result  of 
reasoning.  True  to  our  method,  let  us  appeal  to 
pathology,  for  morbid  cases  often  let  us  perceive 
the  secret  of  the  normal  state. 

Hypnagogic  hallucinations  afford  a  wide  field  of 
observations  and  experiments.  M.  Maury  hit  upon 
the  clever  idea  of  making  experiments  on  his  own 
person,  so  as  to  estimate  to  what  extent  external 
impressions  intervened  in  dreams.  In  the  evening, 
when  he  began  to  fall  asleep  in  his  arm-chair,  he 
asked  a  person  placed  by  his  side  to  produce  sensa- 
tions in  him  without  forewarning  him,  then  to 
awaken  him  when  he  had  already  had  time  to  dream 
a  dream.  The  results  obtained  by  this  method 
really  belong  to  the  study  of  external  perception, 
for  what  is  a  dream  when  produced  under  these 
conditions?  It  is  a  cerebral  reaction  following  an 
impression  of  the  senses — and  this  definition  applies 

*The  same  observations  may  be  advanced  in  the  case  of  those  authors 
who,  like  Hamilton,  Brochard,  James,  Rabier,  etc.,  try,  without  introducing 

Ehysiology,  to  explain  the  resemblance  between  two  states  of  consciousness 
y  the  common  elements  in  the  two  states,  or  by  a  partial  identity  of  their 
elements.  This  pretended  attempt  at  simplification  simplifies  nothing  at  all, 
for  it  replaces  the  idea  of  resemblance  by  the  ideas  of  identity  and  of  unity, 
which  are  merely  its  derivatives.  We  repeat  that  resemblance  is  a  single, 
ultimate  and  irreducible  idea.  (Cf.  Brochard,  De  la  loi  de  similarity  Revue 
philosophique,  March,  1880.) 


130   THE  PSYCHOLOGY  OF  REASONING. 

to  perception.  We  shall  presently  see  that  the 
observer's  dreams  may  be  compared  to  artificial 
illusions  of  the  senses.  Here  are  the  facts: 

His  lips  and  the  end  of  his  nose  are  tickled  with 
a  feather;  he  dreams  that  he  is  undergoing  a  hor- 
rible torture,  that  a  mask  of  wax  is  being  placed  on 
his  face,  then  when  it  is  being  pulled  off,  the  skin 
on  his  lips,  nose  and  face  is  torn.  A  pair  of  tongs 
is  rubbed  with  steel  scissors  a  short  distance  from 
his  ear;  he  dreams  that  he  hears  the  sound  of 
bells;  this  sound  of  bells  soon  becomes  the  tocsin; 
he  thinks  he  is  back  in  the  days  of  June,  1848. 
He  is  made  to  breathe  eau  de  cologne;  he  dreams 
that  he  is  in  a  perfumer's  shop,  and  the  idea  of 
perfume  arouses  that  of  the  Orient;  he  is  at  Jean 
Farina's  shop  in  Cairo.  He  is  made  to  smell  a 
burning  match;  he  dreams  that  he  is  at  sea  (the 
wind  was  then  blowing  on  the  windows)  and  that 
the  Saint c-Barbc  is  pitching.  He  is  pinched  lightly 
on  the  neck;  he  dreams  that  a  blister  is  being 
placed  there,  which  awakens  the  recollection  of  a 
doctor  who  attended  him  in  his  infancy.  A  warm 
iron  is  brought  near  to  his  face;  he  dreams  of 
chauffeurs;  the  idea  of  these  chauffeurs  soon  brings 
that  of  the  Duchess  d'Abrantes,  whom  he  sup- 
poses in  his  dream  to  have  taken  him  as  her  secre- 
tary. He  had  formerly  read  some  details  about 
chauffeurs  in  the  Memoirs  of  that  clever  woman, 
etc.* 

These  experiments  show  that  the  quality  of  the 
sensory  impression  has  an  influence  on  the  nature 

*Maury,  Sommeil  et  reves,  p.  127. 


THE  MECHANISM  OF  REASONING.         131 

of  the  dream,  for  the  trace  of  the  generating  im- 
pression is  found  again  in  the  images  of  fantasy. 

But  some  other  observations  by  the  same  author 
may  be  here  given  which  are  still  more  to  the 
point ;  they  concern  dreams  produced  by  subjective 
sensations.  One  night,  M.  Maury,  when  half 
awake,  sees  a  luminous  spark  (a  subjective  sensation 
of  the  sight) ;  he  immediately  transforms  it,  yield- 
ing already  to  the  desire  for  sleep,  into  a  lighted 
street  lamp.  Then  before  his  eyes  appears  the  Rue 
Hautefeuille,  lit  by  night,  as  he  had  many  a  time 
seen  it  when  he  was  living  in  it,  thirty  years  before. 
The  following  is  another  example  from  the  same 
author:  "When  I  suffer  from  retinal  congestion, 
coloured  patches  and  luminous  circles  shape  them- 
selves upon  my  eye-lid.  Well,  in  the  short  instants 
during  which  imaginary  images  foretell  the  coming 
of  sleep,  I  have  often  found  that  the  luminous 
image  which  was  due  to  the  excitation  of  the  optic 
nerve  was  in  some  way  altered  under  the  eyes  of 
my  imagination,  and  became  transformed  into  a 
countenance  whose  bright  features  represented  those 
of  a  more  or  less  imaginary  person.  It  was  possible 
for  me  to  follow  the  metamorphoses  effected  by  my 
mind  on  this  original  nervous  impression,  for  several 
seconds,  and  I  again  perceived  upon  the  forehead 
and  cheeks  of  these  heads,  red,  blue  or  green 
colour,  a  luminous  brightness  which  shone  before 
my  closed  eyes,  previous  to  the  commencement  of 
the  hypnagogic  hallucination."* 

In  many  similar  cases  it  may  be  found  that  the 

*Op.  fit.,  p.  59. 


132        THE  PSTCHOLOGT  OF  REASONING. 

imaginary  image  of  the  dream  is  preceded  by  phe- 
nomena of  excitation,  which  are  localized,  perhaps 
wrongly,  in  the  retina.  The  subject  who  is  falling 
asleep  begins  by  perceiving  gleams,  confused 
masses  strewn  with  little  coloured  points,  striae  and 
filaments.  The  appearance  of  these  amorphous 
sensations  precedes  the  seeing  of  definite  forms. 
M.  Maury  has  expressed  the  idea  that  the  dream 
hallucination  arises  from  these  "subjective  spec- 
tres," and  is  derived  from  them  by  a  kind  of  trans- 
formation. In  this  case  there  is,  as  M.  Maury  has 
correctly  said,  a  metamorphosis  of  images ;  and  this 
metamorphosis  recalls  that  of  the  zootrope. 

But  in  making  this  comparison  we  either  say 
nothing  at  all,  or  we  affirm  a  certain  fact.  We 
have  seen  how  the  change-effects  produced  by  the 
zootrope  are  explained ;  there  is  a  series  of  impres- 
sions which  follow  each  other  at  very  short  inter- 
vals; these  impressions  are  not  identical,  no  more 
are  they  absolutely  different ;  each  resembles  in  part 
the  one  preceding  and  the  one  following  it.  By 
means  of  this  partial  identity  each  impression 
blends  with  its  neighbour  and  forms  with  it  a  single 
whole.  It  is  this  fusion  of  successive  impressions 
which  gives  the  spectator  the  illusion  of  a  single 
impression.  We  may  suppose,  in  order  to  explain 
the  genesis  of  the  hypnagogic  dream,  that  the 
principle  of  fusion  operates  not  only  between  two 
sensations  and  between  two  images,  but  also 
between  a  sensation  and  an  image. 

This  supposition  enables  us  to  analyze  the 
beginning  of  a  hypnagogic  hallucination  in  the  fol- 


THE  MECHANISM  OF  REASONING.          133 

lowing  manner.  A  luminous  sensation,  a  spark 
for  example,  crosses  the  field  of  vision ;  this  sensa- 
tion recalls,  by  the  effect  of  resemblance,  the  mental 
image  of  an  object  which  also  presents  a  luminous 
point,  for  example  the  image  of  a  lighted  street 
lamp.  Let  us  denote  the  initial  sensation  by  the 
letter  A,  and  the  complex  image  of  a  lighted  street 
lamp  by  the  letters  ABCDEFGH,  etc. ; 
the  letter  A  in  the  second  group  represents  the 
luminous  point  in  the  lamp — that  is  to  say,  the  ele- 
ment which  is  common  to  the  image  of  the  lamp 
and  the  sensation  of  a  spark.  But,  further,  the 
two  elements  represented  by  A  fuse  together  and 
form  a  single  element  in  such  a  way  that  the  image 
evoked  blends  with  the  sensation,  and  the  spark  is 
transformed  into  a  street  lamp ;  then  this  last  image 
recalls  the  entire  image  of  the  street  by  the  associa- 
tion of  contiguity. 

We  find  this  same  fusion  of  sensations  with 
images  in  a  large  number  of  toxic  hallucinations. 
One  woman  who  had  just  taken  some  hashish  in 
order  to  experience  the  blissful  delirium  which  that 
substance  produces  in  the  Orientals,  "saw  her 
brother's  portrait,  which  was  above  the  piano, 
become  animated  and  display  a  forked  pig-tail, 
entirely  black,"  etc.  A  moment  afterward  she 
went  towards  the  door  of  a  neighbouring  room  which 
was  not  lit.  "Then,"  she  says,  "I  experienced  a 
frightful  thing;  I  was  choked  and  suffocated;  I  fell 
into  an  immense  bottomless  pit,  the  well  at  Bicetre. 
Like  a  drowning  man  who  clutches  for  safety  at  a 
frail  straw  which  he  sees  escaping  him,  so  I  tried 


134    TUE  PSYCHOLOGY  OF  REASONING. 

to  catch  on  to  the  stones  which  surrounded  the 
pit;  but  they  fell  with  me  into  that  bottomless 
abyss."  Her  cries  were  heard,  and  she  was 
brought  back  to  the  lighted  part,  and,  her  ideas 
changing  with  the  new  impressions,  she  thought 
she  was  at  the  opera  ball,  and  she  struck  herself 
against  a  stool,  which  she  took  to  be  a  masquerader, 
prone  on  the  floor,  and  dancing  in  an  unseemly 
fashion ;  then  she  walked  in  the  midst  of  a  country 
of  lanterns,  which  phantasmagoria  was  produced 
by  the  flame  of  the  coals  which  burned  in  the  fire- 
place.* When  this  sensory  delirium  is  closely 
studied,  its  development  may  be  readily  followed. 
Its  origin  is  in  the  sensations  of  every  kind  pro- 
duced by  the  external  world  in  the  midst  of  which 
the  patient  moves;  the  impression  of  the  senses  calls 
up  the  images  which  resemble  it;  these  images 
appear,  accumulate,  become  transformed  under  the 
influence  of  the  toxic  agent,  become  separated  more 
and  more  from  their  point  of  origin,  and  finally 
create  an  entirely  imaginary  external  world,  which  a 
new  impulse  of  real  sensations  will  again  come  to 
modify.  But  at  the  first  moment  of  the  evolution 
of  the  delirium,  there  is  always  at  least  a  shade  of 
resemblance  between  the  exterior  object  and  the 
images  which  it  evokes,  as  is  seen  in  the  hallucina- 
tion of  the  well  at  Bicetre,  produced  by  the  dark 
room,  and  it  is  this  resemblance  which  causes  the 
fusion. 

Let   us  pass  to  the  case  of  alcoholic  delirium. 
We    know    that    the    visual    hallucinations    which 

*Moreau  (de  Tours),  Du  hackisch  et  de  I' alienation  mentale,  p.  14. 


THE  MECHANISM  OF  REASONING.          135 

accompany  it  consist  of  terrifying  visions  of  little 
animals,  cats,  rats,  insects,  spiders,  human  heads 
separated  from  their  trunk,  etc.  These  hallucina- 
tions are  not  formed  at  once;  according  to  the  evi- 
dence of  the  best  observers,  the  visions  are  preceded 
by  elementary  troubles  of  a  purely  sensory  charac- 
ter. The  patient  sees  black  points  or  luminous 
spots,  which  are  animated  with  rapid  movement; 
these  are  the  subjective  sensations  from  which  the 
hallucination  is  formed,  and  which  the  brain  of  the 
alcoholic  inebriate  ere  long  transforms,  according  as 
the  delirium  becomes  more  accentuated.  "In  some 
cases,"  says  Magnan,  "the  patient  at  first  sees  a 
dark,  blackish  spot,  with  a  vague  outline,  then  with 
distinct  boundaries  with  prolongations  which  be- 
come legs  and  head,  so  as  to  form  an  animal,  a  rat, 
a  cat,  or  a  man."  Does  this  phenomenon  not 
recall  the  zootropic  metamorphoses  in  a  striking 
fashion?  Is  it  not  quite  naturally  explained  by  a 
fusion  of  sensations  and  images? 

The  same  explanation  may  be  readily  adapted 
to  all  cases  in  which  our  brain  causes  the  sensations 
which  it  receives  to  undergo  a  transformation.  One 
of  the  most  interesting  examples  of  such  transforma- 
tions is  afforded  us  by  what  might  be  called  imagi- 
nary perceptions.  Everybody  must  have  noticed  that 
when  the  environment  is  favourable  one  can  at  will 
picture  to  oneself  the  presence  of  a  certain  body, 
and  perceive  it  as  if  it  actually  existed.  We  distin- 
guish a  great  many  forms  in  clouds,  in  rocks,  in  the 
confused  masses  of  dim  or  distant  objects,  in  the 
flames  of  a  fire,  in  the  inequalities  of  a  wall,  or  in 


136    THE  PSTCHOLOGT  OF  REASONING. 

the  lines,  holes  and  irregularities  of  a  wooden  table. 
It  seems  that  Leonardo  da  Vinci  recommended  his 
pupils,  when  they  were  looking  for  a  subject  for  a 
picture,  to  carefully  study  the  appearance  of  sur- 
faces of  wood ;  in  fact,  at  the  end  of  a  few  minutes 
of  attention,  it  does  not  take  long  to  see  certain 
animal  forms,  human  heads,  and  sometimes  whole 
scenes  picturesquely  arranged,  shape  themselves  in 
the  midst  of  the  confused  lines.  On  this  matter  I 
have  a  fairly  extensive  experience ;  if  I  gaze  attent- 
ively at  a  sheet  of  white  paper,  I  always  discover 
some  figure  on  it;  I  can  even  copy  it,  and  the 
drawings  which  I  obtain  by  this  process  are  gener- 
ally very  superior  to  those  which  I  am  able  to 
produce  by  imagination  alone,  although  in  reality 
they  are  not  worth  very  much ;  but  this  is  a  purely 
relative  matter.  I  have  often  remarked  that  the 
figure  is  not  formed  right  away,  but  slowly  and  by 
degrees,  like  a  piece  of  decoration  which  is  built  up 
of  successive  pieces.  The  important  thing  is  to 
obtain  the  first  form;  if  it  is  fairly  vivid,  it  will  not 
be  long  in  completing  itself,  the  edifice  being 
noiselessly  constructed  on  that  first  stone. 

It  would  be  exceedingly  interesting  to  study 
this  imaginative  side  of  our  nature.  The  germ  of  a 
theory  of  invention,  more  genuine  than  all  those 
which  we  have  so  far  obtained,  might  perhaps 
indeed  be  found  therein.  However  that  may  be, 
it  is  important  for  us  to  observe  that  the  mind,  in 
these  perceptions,  works  on  the  fortuitous  resem- 
blances which  it  discovers  in  an  object ;  it  is  through 
these  points  of  resemblance  that  the  imaginary 


THE  MECHANISM  OF  REASONING.          137 

image  is  evoked  and  becomes  blended  with  the  sen- 
sible impression.  At  the  same  time,  which  is  a 
curious  thing,  the  mind  systematically  neglects  all 
the  characteristics  of  the  external  object  which  do 
not  harmonize  with  this  fiction. 

Imaginary  perceptions  belong  to  the  same  family 
as  illusions  of  the  senses;  they  might  be  defined 
as  voluntary  illusions.  They  are  the  dramas  of 
which  we  are  at  once  author  and  spectator. 
Involuntary  illusions  supply  us  with  similar  facts. 
Every  time  that  an  illusion  lends  itself  to  analysis, 
it  is  perceived  that  the  false  exteriorized  image, 
which,  properly  speaking,  constitutes  the  illusion, 
in  some  way  resembles  that  which  gave  it  birth. 
For  example,  when,  by  reason  of  distance  or  ob- 
scurity, we  take  one  person  for  another,  or  allow 
ourselves  to  be  deceived  by  an  imperfect  resem- 
blance, we  commit  an  error  of  identification;  in 
other  words,  the  first  image  awakened  by  the  exter- 
nal sensations  resembles  them  and  is  blended  with 
them.  This,  moreover,  is  confirmed  by  hypnotic 
experiments.  Move  your  hand  before  the  eyes  of 
a  somnambulist,  imitating  the  movement  of  wings 
with  your  fingers;  he  immediately  sees  a  bird  and 
tries  to  catch  it.  Imitate  a  reptile's  movement  with 
your  hand  on  the  ground,  and  he  sees  a  serpent. 
The  general  rule  is  that  the  subject  sees  all  the  ob- 
jects whose  appearance  is  simulated. 

We  pass  by  an  insensible  transition  from  the 
illusion,  or  false  perception,  to  true  perception. 
Let  us  see  if  every  act  of  perception  likewise  takes 
its  rise  in  an  act  of  identification. 


138    THE  PSTCHOLOGT  OF  REASONING. 

I  take  hold  of  a  book  on  a  table;  I  lift  it,  open  it, 
turn  over  its  leaves,  read  it,  and  close  it.  All  these 
acts  have  aroused  a  large  number  of  impressions  of 
touch,  form,  weight,  temperature,  resistance  and 
movements  in  me,  which  are  united  together  and 
associated  with  the  visual  impressions  which  I  felt 
at  the  same  time.  Let  us  now  suppose  that  I  leave 
my  room,  and  return  to  it  after  some  minutes' 
absence.  The  book  is  still  in  the  same  place ;  if  I 
look  at  it,  the  visual  impression  which  I  experience 
awakens  in  my  memory  the  images  of  sensations  of 
all  kinds  which  I  received  when  handling  it  a  short 
time  before.  In  short,  images  of  touch,  of  the 
muscular  and  other  senses  proceed  to  combine  with 
the  visual  sensation.  Perception  therefore  takes 
place. 

But  how  does  it  happen  that  this  new  visual 
sensation  can  awaken,  under  an  ideal  form,  these 
impressions  formerly  received  by  the  hand?  There 
is  in  this  case  no  bond  of  resemblance,  nor  even 
any  bond  of  contiguity,  for  the  actual  sensation  of 
sight  is  absolutely  new,  and  could  not  become  asso- 
ciated with  impressions  received  by  the  hand  several 
minutes  before.  There  is  one  reply,  and  only  one, 
to  this  question ;  it  is  that  the  actual  aspect  of  the 
book  resembles  in  part  or  in  totality  the  former 
aspect,  the  recollection  of  which  persists  in  my 
mind.  From  my  preceding  experience  there  sur- 
vives an  ocular  image  of  the  book,  associated  with 
impressions  from  the  hand.  The  appearance  of  the 
book  as  actually  seen  is  fused  with  this  visual  recol- 
lection, which  in  its  turn  brings  the  train  of  tactile 


THE  MECHANISM  GF  REASONING.          139 

and  muscular  recollections  to  which  it  is  bound 
into  the  field  of  consciousness. 

According  to  this  interpretation,  the  series  of 
states  of  consciousness  which  succeed  each  other  in 
perception  is  as  follows: 

The  actual  vision  of  the  book  (A)  excites  in  our 
thought,  by  the  force  of  similarity,  the  ocular  image 
of  the  same  book  (B)  which  is  due  to  a  former 
vision,  and  this  second  state  of  consciousness  in 
its  turn  excites,  by  the  force  of  contiguity,  the 
group  of  tactile  and  muscular  impressions  (C).  It 
is  the  state  of  consciousness  (B)  which  enables  the 
first  state  to  excite  the  third;  so  I  propose  to  call  it 
the  intermediate  state  of  consciousness,  in  order  to 
express  its  function. 

The  curious  fact  is  that  this  image  (B),  the 
visual  recollection  of  the  book,  does  not  make  its 
appearance,  in  spite  of  the  importance  of  the  part  it 
plays.  When  we  look  at  the  book,  we  do  not  have, 
simultaneously  with  this  vision,  the  distinct  recol- 
lection of  a  former  vision.  Yet  this  recollection 
constitutes  an  indispensable  part  of  the  operation, 
for  without  it  perception  would  be  impossible;  it  is 
in  a  manner  "invisible  and  present;"  it  is  fused 
with  the  visual  sensation  of  the  moment,  and  be- 
comes one  with  it,*  so  that  this  sensation  is  found 
directly  associated  with  the  group  of  tactile  and 
muscular  images. 

Let  us  represent  the  course  of  the  phenomenon 
graphically. 

*\Ve  assume,  for  the  sake  of  simplicity,  that  the  actual  vision  of  the 
book  and  the  visual  recollection  of  the  same  object  completely  resemble  each 
other,  and  that  the  fusion  is  total;  if  the  resemblance  is  only  partial,  the 
fusion  also  is  partial. 


140         THE  PSYCHOLOGY  OF  REASONING. 

The  perception  of  the  book  has  the  effect  of 
uniting  a  visual  sensation  to  a  group  of  tactile  and 
muscular  images.  The  formation  of  this  associa- 
tion constitutes  the  conclusion  of  the  perceptive 
reasoning.  This  mental  synthesis  may  be  expressed 
by  the  formula 

A-C 

in  which  A  represents    the   actual   vision    of   the 
book,  C  the  group  of  muscular  and  tactile  images 
— that  is  to  say,  the  fact  inferred,  and  the  sign  - 
the  bond  of    association   which   unites  these    two 
terms.  * 

The  psychological  question  which  now  arises  is, 
as  we  have  shown  above,  to  explain  the  formation 
of  this  association.  Now,  we  say  that  the  actual 
vision  of  the  object  begins  by  reminding  us  of  a 
former  vision  by  means  of  the  resemblance  between 
these  two  states.  This  again  may  be  represented 
symbolically  in  the  following  manner: 

A=B 

In  this  formula  A  continues  to  represent  the 
actual  vision  of  the  book  placed  before  our  eyes,  B 
represents  the  recollection  of  a  former  vision  of  that 
same  book — that  is  to  say,  its  visual  image — and 
the  sign  =  indicates  the  resemblance  between  the 
sensation  and  the  image.  This  identification  is,  in 

•We  employ  algebraic  signs  merely  in  order  to  represent  in  a  graphic 
manner  the  properties  of  the  images  which  cooperate  in  an  act  of  reasoning. 
It  must  be  added  that  in  no  way  do  we  place  ourselves  at  the  point  of  view  of 
English  logicians  such  as  De  Morgan,  Boole,  and  Stanley  Jevons,  who  also 
make  use  of  these  signs,  but  for  the  purpose  of  putting  the  problem  of  logic 
in  the  form  of  an  equation,  and  of  solving  it  by  processes  more  or  less  analo- 
gous to  those  of  algebra.  Consult  on  this  subject  the  interesting  work  of 
Louis  Liard,  Les  logitiens  anglais  contemporains.) 


THE  MECHANISM  OF  REASONING.          141 

our  opinion,  the  first  part,  the  first  act  of  external 
perception. 

In  this  case  there  is  not  only  a  recollection,  a 
calling  up  of  the  image  B,  but  this  image,  when 
once  evoked,  becomes  fused  with  the  sensation  A, 
like  the  two  sensations  of  the  points  of  the  com- 
passes in  Weber's  experiment.  There  is  nothing 
astonishing  in  this  result  if  we  recollect  that  an 
image  is  almost  a  sensation.  We  have  devoted  a 
chapter  to  demonstrating  that  fact.  We  may  there- 
fore indicate  this  fusion  in  the  following  manner, 
which  has  the  advantage  of  appealing  to  the  eye : 

[A=B] 

In  this  new  formula  the  brackets  express  the 
fusion  of  the  sensation  and  the  image. 

Here  the  first  act  of  perception  finishes  and  the 
second  begins.  We  have  assumed  in  our  example 
that  former  experiences  had  cemented  an  associa- 
tion between  the  vision  of  the  book  and  the  exceed- 
ingly diverse  sensations  which  this  object  produces 
when  we  take  it  up,  open  it  and  read  it,  sensations 
the  recollection  of  which  has  been  designated  by 
the  letter  C.  This  may  be  represented  thus: 

B-C 

a  formula  in  which  B  still  represents  the  former 
vision  of  the  book,  C  the  experiences  of  active 
touch,  and  the  sign  —  the  pre-formed  association 
between  these  two  images. 

We  therefore  say  that,  through  the  fact  of  the 
fusion  of  A  and  B — that  is  to  say,  in  consequence 


142         THE  PSTCHOLOGT  OF  REASONING. 

of  the  fusion  of  the  actual  vision  with  the  visual 
recollection  of  the  object — C  is  associated  directly 
with  A,  or,  in  other  words,  the  idea  of  the  invisible 
attributes  of  the  object  is  directly  associated  in  our 
mind  with  its  visual  aspect.  Finally,  we  arrive  at 
this  last  formula,  which  is  self-explanatory : 

[A  =  B]-C 

To  sum  up,  the  whole  operation  may  be  analyzed 
thus:  An  association  by  resemblance,  the  purpose 
of  which  is  to  introduce  an  association  by  contiguity. 
As  the  latter  is  the  end,  it  diverts  the  attention 
from  the  former,  which  is  the  means. 

It  would  be  easy  to  simplify  the  description  of 
this  operation  by  showing  that  it  may  be  reduced 
to  the  partial  assimilation  of  two  images.  In  fact, 
perception  is  produced  by  the  partial  fusion  of  the 
ocular  sensation  which  the  object  actually  produces 
upon  us  with  the  complete  recollection  of  the  same 
object,  or  of  a  similar  object,  which  lives  in  our 
memory.  This  assimilation  of  two  impressions  is 
the  biological  property  from  which  reasoning 
springs. 

We  began  by  offering  this  mechanism  of  percep- 
tion as  a  hypothesis.  But  if  this  explanation  be 
compared  with  all  the  pathological  facts  which  have 
been  cited,  it  will  be  recognized  that  the  hypothesis 
very  nearly  attains  to  the  rank  of  theory.  We  have 
seen  that  in  all  the  morbid  perceptions  which  lend 
themselves  to  analysis,  the  phenomenon  begins  with 
an  act  of  identification — that  is  to  say,  by  a  fusion 
of  the  excitative  sensation  with  the  first  image  which 


THE  MECHAXISM    OF  REASONING.          143 

it  evokes.  We  may  recall,  among  the  most  typical 
cases,  the  sleeper  who,  seeing  a  spark,  transforms  it 
into  a  lighted  street-lamp,  and  sees  a  street  lit  at 
night  appearing  before  him ;  the  alcoholic  inebriate 
who,  seeing  black  points  moving  in  his  field  of 
vision,  transforms  them  into  little  black  beasts  with 
lengthening  legs;  the  wide-awake  person  who,  by 
fixing  his  attention  on  the  confused  lines  on  a  table, 
finishes  by  seeing  fixed  forms  come  out  of  them; 
and,  finally,  the  individual  affected  by  an  illusion  of 
the  senses,  who  confounds  a  stranger  with  a  friend, 
letting  himself  be  deceived  by  a  rough  resemblance 
of  size,  of  figure,  or  of  dress.  Always  and  every- 
where external  perception,  whether  it  be  exact, 
whether  it  be  false  (illusion),  or  whether  it  be  insane 
(hallucination),  takes  its  rise  in  a  fusion  between  the 
sensations  of  the  external  world  and  the  images 
which  these  sensations  cause  to  spring  up  in  the 
mind. 

The  only  difference  is  that  in  false  and  patholog- 
ical perceptions  a  shade  of  resemblance  is  sufficient 
to  produce  suggestion,  while  in  correct  perception 
we  only  take  account  of  an  ensemble  of  resem- 
blances, and  even  a  shade  of  difference  is  enough  to 
prevent  suggestion.  Helmholtz  has  remarked  that 
in  the  stereoscopic  arrangement  the  presence  of  a 
badly-projected  shadow  destroys  the  illusion.  But 
we  are  obliged,  in  the  interests  of  clearness,  to  put 
aside  these  details.  All  that  we  retain  of  the  pre- 
ceding discussion  is  the  fact  that  perception  takes 
its  rise  in  identification. 

Moreover,   how  could  it  be  otherwise?     When 


144    THE  PSTCHOLOGT  OF  REASONING. 

we  perceive  an  external  object,  we  receive  sensa- 
tions which  are  always  new  and  distinct  from  all 
those  which  have  preceded  them.  How  then  could 
those  new  sensations  evoke  past,  former  states, 
such  as  images,  if  not  by  the  effect  of  resemblance? 
Resemblance  is  the  only  bond  which  could  unite 
states  separated  by  time.  Let  us  state  this  problem 
in  an  a  priori  form,  employing  the  formulae  which 
we  have  already  made  use  of.  On  the  one  hand,  B 
is  associated  with  C.  On  the  other  hand,  A  resem- 
bles B.  How  can  A  become  associated  with  C,  if 
not  through  the  medium  of  B? 

Before  going  further,  we  wish  to  show  that  these 
complex  phenomena  in  which  similarity  and  con- 
tiguity are  combined  have  already  been  noticed  by 
psychologists,  although  they  did  not  understand 
their  significance.  Two  passages  may  be  read  in 
this  connection,  one  from  James  Mill  (Analysis  of 
the  Phenomena  of  the  Human  Mind,  Vol.  I,  p.  in, 
et  seg.^j  and  the  other  from  Mr.  Bain  (eod.  loc.,  p. 
464,  et  seq.~).  We  shall  quote  only  Mr.  Sully,  who 
remarks,  in  his  book,  entitled  Outlines  of  Psy- 
chology, that  the  two  laws  of  contiguity  and  simil- 
arity are  at  once  distinct  and  inseparable.  "Each 
mode  of  reproduction  may  be  said  to  involve  the 
cooperation,  in  different  proportions,  or  with  differ- 
ent degrees  of  distinctness,  of  two  elements,  a  link 
of  similarity  or  identity  and  a  link  of  contiguity. 
Thus  when  a  person's  name  calls  up  the  image  of 
his  face,  it  is  because  the  present  sound  is  automat- 
ically identified  with  previously  heard  sounds.  So, 
too,  revival  by  similarity  commonly  involves  con- 


THE  MECHANISM  OF  REASONING.         145 

tiguity  as  shown  above.  But  in  ordinary  cases 
what  we  call  revival  by  similarity  involves  the  call- 
ing up  of  concomitant  circumstances."  The  author 
symbolizes  the  relation  between  the  two  laws  as  fol- 
lows: 

A  A 


Contiguity 


Similarity 


(a)  — n  c  —  (a)  —  f . 

In  the  first  case  the  process  of  identification  be- 
tween A  and  (a)  is  automatic  or  unconscious,  and 
the  revived  concomitants  (n)  are  thought  of  as  quite 
distinct  from  that  which  revives  them ;  whereas  in 
the  second  case  the  identification  is  the  important 
step  in  the  process,  and  the  concomitants  (c  and  f) 
are  not  distinctly  separated  from  the  identified 
element  (a).  We  have  only  to  compare  this  plan 
with  our  own  to  recognize  the  identity  of  the  two: 
First  of  all  we  see  therein  the  fusion  of  one  state  of 
consciousness  with  a  second  similar  state,  then  the 
suggestion  of  a  third  state  which  was  associated  with 
the  second  by  contiguity. 

But  what  is  yet  more  important  to  notice  is  that 
the  process  of  perception  which  we  have  described 
is,  according  to  Stuart  Mill,  Mr.  Bain  and  Mr. 
Sully,  a  general  process,  which  is  realized  every 
time  that  an  association  of  ideas  comes  into  play — 
that  is  to  say,  at  every  instant  in  our  lives.  Now, 
as  we  shall  presently  proceed  to  demonstrate  the 
logical  value  of  this  process,  which  constitutes  true 
reasoning,  we  shall  consider  reasoning,  not  as  an 
accidental  fact,  but  as  the  constant  element  in  our 


146    THE  PSTCHOLOGT  OF  REASONING. 

lives,  the  fabric  of  all  our  thoughts.  Thus,  we  shall 
come  to  accept  as  a  demonstrated  truth  that  appar- 
ent paradox  of  Wundt's :  The  mind  might  be  defined 
as  a  thing  which  reasons. 

III. 

The  phenomena  which  we  are  at  present  study- 
ing are  so  important  that  we  are  willing  to  protract 
the  examination.  Perception,  we  have  said,  is  an 
operation  in  three  terms ;  we  have  seen  how  many 
proofs  lend  support  to  this  proposition.  But  we 
wish  to  continue  the  demonstration  to  its  conclusion 
by  quoting  examples  of  perceptions  in  which  the 
distinct  existence  of  these  three  terms  may  be 
directly  recognized  by  inspection  alone.  This 
occurs  whenever  perception,  in  evolving  and  becom- 
ing complicated,  tends  to  become  confused  with 
conscious  and  voluntary  reasonings. 

Let  us  take  a  simple  example,  which  we  shall 
afterwards  try  to  complicate.  In  what  does  the 
process  of  reading  a  written  word  consist?  At  first 
sight  it  is  merely  bringing  an  association  of  con- 
tiguity between  a  graphic  sign  and  an  idea  into 
operation.  When  the  graphic  sign  is  very  clear, 
like  a  printed  letter,  the  suggestion  of  the  image 
follows  the  seeing  of  the  sign  immediately;  the 
operation  appears  to  be  in  two  terms,  like  the  ma- 
jority of  our  ordinary  perceptions.  For  example, 
the  image  of  a  house  appears  vaguely  when  we  read 
the  word  ' '  house. ' '  But  let  us  complicate  the  opera- 
tion a  little ;  let  us  try  to  retard  it  in  order  to  grasp 
it  better  in  detail,  and  a  supplementary  term  is  im- 


THE  MECHANISM  OF  REASONING.         147 

mediately  detached.  We  take,  in  place  of  a  printed 
word,  a  word  written  by  the  hand  and  almost 
illegible.  Then  we  perceive  that  the  sight  of  the 
characters  is  not  enough  to  make  them  understood ; 
it  is  necessary,  in  addition,  to  recognize  them,  to 
state  that  this  disfigured  letter  is  an  a,  this  other  a 
c,  and  so  on.  But  how  is  this  recognition  possible, 
if  not  by  a  comparison  between  the  altered  character 
and  the  recollection  of  the  normal  character?  We 
decide  that  this  letter  is  an  a  by  ascertaining  that  it 
more  or  less  resembles  the  letter  a  which  we  know. 
Eliminate  this  recollection,  this  intermediate  state 
of  consciousness,  and  the  operation  becomes  impos- 
sible. 

There  are  numerous  examples  of  the  same  kind. 
One  more  may  be  given.  There  are  some  diag- 
noses which  are  made  at  a  distance,  so  far  as  they 
are  easy;  a  neuro-pathologist  has  often  merely  to  see 
a  sufferer  from  ataxia  walking,  or  a  paralytic  (Park- 
inson's disease)  moving  in  the  street  in  order  to 
recognize  their  disease.  The  mere  sight  of  a  prom- 
inent symptom  evokes  the  name  of  the  disease,  and 
the  representation  of  all  the  other  symptoms  which 
belong  to  the  same  affection.  But  most  frequently 
the  sight  and  even  the  methodical  examination  of 
the  patients  is  not  enough;  the  physician  must 
gather  his  recollections  together  in  order  to  make 
the  diagnosis.  What  does  he  do  then?  He  com- 
pares the  case  he  has  before  him  with  analogous 
cases  which  have  already  occurred.  Trousseau 
even  said  that  in  this  work  of  comparison  he  dis- 
tinctly remembered  patients  whom  he  had  formerly 


148    THE  PSTCHOLOGT  OF  REASONING. 

seen  in  the  hospital  while  he  was  a  student;  he 
pictured  their  appearance,  and  even,  he  says,  the 
number  of  their  bed.  This  conscious  reversion  to 
previous  and  similar  cases  brings  the  intermediate 
state  of  consciousness  prominently  into  view.  This 
state  is  always  apparent  when  the  similarity  does 
not  operate  in  a  sure  and  infallible  manner. 

We  may  therefore  affirm  that  three  images  suc- 
ceed each  other  in  the  perception  of  an  external 
object.  We  have  still  to  show  the  importance  of 
this  analysis.  It  is  exact,  it  may  be  said,  but  what 
is  the  use  of  it?  It  describes  for  describing's  sake; 
it  supplies  no  information  as  to  the  mechanism  of 
reasoning;  after  having  engaged  in  a  minute  psy- 
chological dissection,  we  know  no  more  of  the  mat- 
ter than  we  did  before. 

Our  aim  is  to  show  briefly,  and  above  all  as 
clearly  as  possible,  the  significance  of  the  results 
obtained.  We  are  convinced  that  we  are  now  able 
to  give  an  exact  theory  of  the  mechanism  of  reason- 
ing; in  fact,  thanks  to  this  supposition  that  in  every 
perception  there  exists  an  intermediate  state  of  con- 
sciousness (B),  serving  as  the  connecting  link  be- 
tween the  impression  of  the  senses  (A)  and  the 
inferred  images  (C),  everything  becomes  clear;  this 
supposition  is  like  the  word  which,  interpolated  in 
a  mutilated  text,  reveals  its  meaning.  We  shall 
presently  see  that  we  can  recognize,  in  the  account 
of  perception  reconstituted  in  this  manner,  all  the 
parts  which  go  to  form  a  regular  act  of  reasoning. 

First  of  all,  the  act  of  perception  becomes  a 
transition  from  the  known  to  the  unknown  by 


THE   MECHANISM  OF  REASONING.          149 

means  of  a  resemblance,  and  it  will  be  remembered 
that  this  is  a  rough,  though  exact,  definition  of 
reasoning.  The  known  fact  is  the  sensation  which 
we  actually  experience,  for  example,  the  visual 
sensation  of  a  book  placed  on  a  table.  The  un- 
known fact  is  the  nature  of  the  object  which  gives 
us  this  visual  sensation.  We  obtain  this  desired 
idea  through  the  suggestion  of  a  recollection — the 
image  of  a  book;  now,  the  transition  from  the  sen- 
sation to  the  image,  from  the  known  fact  to  the 
unknown  fact,  is  afforded  us  by  the  resemblance 
of  the  visual  object  to  the  object  with  which  we 
identify  it. 

It  will  perhaps  be  said  that  reasoning  is  some- 
thing mor-e  than  this  consecution  of  images ;  it  is  a 
judgment,  it  is  the  formation  of  a  new  belief. 
Therefore  it  is  not  sufficient  to  explain  how  the 
complete  and  detailed  image  of  the  book  can  be 
called  forth  on  account  of  an  elementary  sensation 
of  sight  or  of  touch ;  it  would  still  be  necessary  to 
give  an  account  of  this  new  belief  which  enables  us 
to  affirm  that  "this  is  a  book."  The  suggestion  of 
a  fact  is  one  thing,  and  the  judgment  which  accepts 
it  as  true  is  another.  For  example,  we  shall  not 
explain  the  reasoning  which  makes  us  say  that  Paul 
is  mortal,  if  we  merely  show  how  the  idea  of  the 
death  of  this  individual  comes  to  our  mind;  as  we 
may  yet  state  how  this  idea  determines  our  convic- 
tion. Such  is  the  objection  which  certain  readers 
will  not  fail  to  offer.  Let  us  try  to  reply  to  it. 

Belief,  conviction  and  assent  are  among  those 
vague,  liquescent  and  ill-defined  phenomena  which  are 


150         THE  PSYCHOLOGY  OF  REASONING. 

numerous  in  psychology;  they  could  with  difficulty 
be  made  the  subject  of  methodical  study.  But 
psychologists  have  adopted  a  bias;  they  have 
remarked  that  belief  generally  resulted  from  a  rela- 
tion between  images.  When  two  facts  have  often 
occurred  at  the  same  time  or  in  immediate  succes- 
sion, the  corresponding  images  have  a  tendency  to 
become  connected  in  our  mind,  and,  further,  we 
have  a  tendency  to  believe  that  the  phenomena, 
the  ideas  of  which  are  associated  in  our  mind,  are 
likewise  associated  in  reality.  (See  p.  79.)  This 
stated,  it  is  clear  that  a  theory  will  explain  the 
formation  of  a  new  belief  if  it  explains  not  only  the 
suggestion  of  the  idea  to  be  affirmed,  but  the  asso- 
ciation, the  organization  of  this  idea  with  others. 
Let  us  repeat  our  argument,  so  as  to  make  it  clearer. 
We  admit  that  it  is  not  sufficient  to  say,  in  order  to 
explain  our  reasoned  conviction  that  a  certain  man 
must  die,  how  we  obtain  the  idea  of  the  death  of  a 
man ;  but  the  moment  we  explain  how  this  idea  of 
death  becomes  associated  with  that  of  the  individual 
in  question,  so  as  to  produce  the  belief  that  he  is 
mortal,  we  haye  attained  our  end,  and  demonstrated 
that  which  required  demonstration. 

Well,  has  this  demonstration  been  furnished? 
Has  the  preceding  analysis  explained  how,  apart 
from  all  experience,  merely  by  an  operation  of 
mental  laws,  an  association  can  be  formed  between 
two  images?  This  was,  it  will  be  remembered,  one 
of  the  conditions  which  we  had  urged  (p.  94) 
against  every  explanation  of  reasoning — this  condi- 
tion seems  to  us  to  be  fulfilled.  We  have  seen  the 


THE  MECHANISM  OF  REASONING.          151 

reason  why  the  detailed  image  of  the  book  is  com- 
bined with  the  visual  sensation  of  the  moment;  it  is 
because  these  two  impressions  have  points  of  resem- 
blance which  weld  them  together.  Thus  are  ex- 
plained all  the  syntheses  of  our  sensations  and  of 
our  recollections. 

But  that  is  not  all;  a  reasoned  conclusion  does 
not  merely  include  an  adoption  of  a  new  truth. 
This  truth  also  presents  that  particular  character  of 
being  a  logical  consequence  of  a  truth  already 
admitted.  In  psychological  terms  the  association 
of  images  which  is  established  by  reasoning  takes 
place  through  the  medium  of  preexisting  associa- 
tions which  are  called  premisses.  To  reason  is  to 
establish  associations  on  the  model  of  other  associ- 
ations which  are  already  formed.  (See  p.  95.)  It 
remains  to  show  that  our  thesis  on  the  mechanism 
of  perception  gives  an  account  of  this  latter  charac- 
ter of  reasoning.  To  this  end,  we  must  establish  a 
new  parallel  between  external  perception  and  the 
syllogism. 

In  the  first  place,  it  will  be  observed  that  per- 
ception is  an  operation  in  three  terms,  A,  B,  C. 
The  first  term  (A)  represents  the  actual  vision  of  the 
object,  the  second  (B)  its  former  vision,  and  the 
third  (C)  the  inferred  properties.  The  syllogism  is 
also  an  operation  in  three  terms;  in  the  example 
which  we  analyzed  before,  these  terms  are  Socrates, 
man  and  mortal, 

Again,  in  the  syllogism  the  mean  term  enters 
into  the  major  and  the  minor  and  disappears  in  the 
conclusion,  although  it  is  preparatory  to  it.  It  is 


152         THE  PSYCHOLOGY  OF  REASONING. 

the  term  "man."  Reasoning,  as  Boole  remarks, 
is  the  elimination  of  a  mean  term  in  a  system  of 
three  terms.  This  mean  term,  we  say,  is  prepara- 
tory to  the  conclusion ;  for  if  Socrates  were  not  a 
man,  he  would  not  be  mortal.  Similarly  in  percep- 
tion, the  term  B,  the  visual  recollection  of  the 
object,  is  a  true  mean  term ;  on  the  one  hand,  it 
vanishes  when  we  reach  the  conclusion,  for  it  blends 
with  the  actual  vision  (A) ;  on  the  other  hand,  it  is 
preparatory  to  the  conclusion,  for  if  the  actual  aspect 
of  the  object  did  not  resemble  the  former  aspect 
already  seen  (B),  we  would  not  be  able  to  recog- 
nize it. 

But  the  parallel  may  be  pushed  much  further. 
It  is  possible  to  divide  the  act  of  perception  into 
three  slices,  as  is  done  with  the  syllogism — that  is 
to  say,  into  three  parts  which  correspond  to  the 
three  verbal  propositions  of  an  act  of  logical  reason- 
ing. 

Let  us  begin  by  translating  the  familiar  syllo- 
gism, which  we  have  used  so  often,  into  psychological 
language.     Let  us  take  the  major  premiss  first : 
All  men  are  mortal. 

This  proposition  states,  according  to  a  logician's 
analysis,*  that  the  attributes  connoted  by  "man" 
never  exist  unless  conjoined  with  the  attribute 
called  mortality,  so  that  wherever  the  first  attribute 
is  found  we  may  be  sure  of  the  existence  of  the 
second.  It  is  a  relation  between  two  facts.  Psy- 
chologically, the  proposition  has  another  meaning; 
it  means  that  there  exists  in  our  mind  an  associa- 

*John  Stuart  Mill,  Logic,  p.  122. 


THE  MECHANISM  OF  REASONING.          153 

tion  between  two  groups  of  images,  one  group  of 
abstract  images  representing  man,  and  one  group  of 
generic  images  representing  death.  We  understand 
by  the  word  association  that  these  two  images  are 
produced  simultaneously  or  in  immediate  succession 
in  our  mind.  We  say  again  that  the  two  images 
are  contiguous.  Consequently  we  shall  call  our 
major  proposition  a  proposition  of  contiguity.  It 
is  to  our  past  experience,  or  to  the  testimony  of 
others,  that  we  owe  that  association;  it  is  given, 
acquired,  considered  as  corect,  at  the  moment  when 
we  perform  the  act  of  reasoning.  It  is  upon  it  that 
our  conclusion  will  depend. 

The  minor  premiss  of  the  reasoning 

Socrates  is  a  man, 

is  of  another  nature.  It  signifies  from  the 
logical  point  of  view  that  there  is  a  perfect  resem- 
blance, an  identity,  between  certain  attributes  of 
Socrates  (colour,  form,  size,  internal  structure)  and 
the  attributes  of  humanity.  That  is  what  the 
proposition  signifies;  now,  as  a  distinct  question, 
what  is  it  from  the  psychological  point  of  view?  It 
is  an  act  of  assimilation  between  the  image  of  cer- 
tain attributes  of  Socrates  and  the  generic  image  of 
humanity.  Here  the  mind  seizes  a  resemblance 
between  two  groups  of  images,  and  the  proposition 
which  expresses  this  internal  act  may  be  called  a 
proposition  of  resemblance. 
The  conclusion 

Socrates  is  mortal, 

contains  the  truth  discovered  by  deduction.  Con- 
sidered from  the  objective  point  of  view,  it  signifies 


154    THE  PSYCHOLOGY  OF  REASONING. 

that  there  exists  a  relation  of  coexistence  between 
the  individual  called  Socrates  and  the  attributes  of 
mortality,  or,  in  other  words,  that  Socrates  pos- 
sesses these  attributes.  Psychologically,  this  prop- 
osition indicates  that  a  relation  of  contiguity  has 
been  established  in  our  mind  between  the  image  of 
Socrates  and  the  image  of  mortality. 

To  sum  up,  the  preceding  reasoning  may  be 
divided  into  three  propositions:  (i)  A  proposition 
of  coexistence,  the  major  premiss;  (2)  a  proposition 
of  resemblance,  the  minor  premiss;  (3)  a  proposi- 
tion of  coexistence,  the  conclusion.* 

Now,  let  us  put  the  propositions  of  the  syllogism, 
on  the  one  hand,  opposite  the  symbolic  formulae 
which  we  employed  in  our  analysis  of  perception, 
on  the  other  hand  : 

Major  premiss:  All  men  are  mortal  B— C 
Minor  premiss:  Socrates  is  a  man  A=B 
Conclusion:  Socrates  is  mortal  (A=B)— C 

The  major  premiss  of  our  syllogism  is,  we  have 
said,  a  proposition  of  coexistence;  it  signifies  that 
the  generic  image  of  man  is  associated  in  our  mind 
with  the  abstract  image  of  mortality.  Similarly,  in 
the  formula  B — C  we  find  an  association  of  images 
indicated ;  for  this  formula  means  that  the  former 

*According  to  Mill  (of.  cit.,  p.  123,),  the  principle  involved  in  every 
inference  strikingly  resemmes  the  axioms  of  mathematics.  It  is  that 
"things  which  coexist  with  the  same  thing,  coexist  with  one  another."  Thus: 
Socrates  coexists  with  man. — Mortality  coexists  with  man. — Therefore 
Socrates  and  mortality  coexist  with  one  another.  But  there  is  an  error  in 
this  analysis:  in  reality  the  reasoning:  is  not  composed  of  three  propositions 
of  coexistence.  The  minor  premiss  is  a  proposition  of  resemblance.  To  say 
that  Socrates  is  a  man  means  that  he  resembles  men  whom  we  know.  Mill 
himself  remarks  this  (p.  383).  So  we  ought  rather  to  say:— Socrates  resembles 
man— man  coexists  with  mortality — Socrates  coexists  with  mortality.  If  it 
were  desired  that  a  principle  should  be  deduced  from  this  operation  at  all 
costs,  we  would  propose  the  following:  "A  thing  which  resembles  another 
thing  communicates  to  it  the  property  which  it  has  of  coexisting  with  a 
third. 


THE  MECHANISM   OF  REASONING.          155 

vision  of  the  book  (B)  is  associated  with  the  image 
of  its  tangible  qualities  (C).  Therefore,  on  both 
sides  there  is  the  same  association  of  contiguity. 

The  minor  premiss  of  our  syllogism  expresses  a 
resemblance  between  the  mental  representation  of 
Socrates  and  that  of  the  attributes  connoted  by  the 
word  humanity.  In  the  formula  A=B,  there  is  also 
an  identification  between  the  actual  vision  of  the 
book  (A)  and  the  recollection  of  a  former  vision  (B) 
— that  is  to  say,  between  the  sensation  and  the 
image  of  one  and  the  same  thing.  Therefore,  on 
both  sides  there  is  the  same  association  of  resem- 
blance. 

Finally,  the  conclusion  of  our  syllogism  indicates 
that  an  association  of  contiguity  exists  between  the 
image  of  Socrates  and  the  image  of  death.  In  the 
formula  (A=B) — C,  we  also  see  an  association  of 
contiguity  become  formed  between  the  vision  of  the 
book  and  the  idea  of  its  tangible  attributes.  There- 
fore, there  is,  once  more  on  both  sides,  the  same 
association  of  contiguity. 

It  would  be  superfluous  to  dwell  further  on  this 
matter.  Perception  is  evidently  composed  of  the 
same  parts  as  formal  reasoning.  But  the  direct 
study  of  formal  reasoning  cannot  lead  to  a  theory 
of  that  operation,  for  the  states  of  consciousness 
which  are  its  subject  are  too  complicated  for  one  to 
be  able  to  observe  the  law  according  to  which  they 
are  connected.  When  I  say,  "All  men  are  mortal; 
Socrates  is  a  man,  therefore  he  is  mortal,"  what 
takes  place  in  my  mind?  Of  that  I  know  nothing 
accurately.  I  seem  to  perceive  a  train  of  confused 


156    THE  PSTCHOLOGr  OF  REASONING. 

images.  In  any  case  I  am  unable  to  understand  how 
these  images  are  connected  and  disposed  in  reasoning. 
I  am,  to  employ  one  of  Wundt's  comparisons,  like  a 
physicist  who  wished  to  study  the  vibrations  of  a 
pendulum  by  looking  at  them  through  a  keyhole, 
or  like  an  astronomer  who,  to  study  the  sky,  took 
up  his  residence  in  a  cellar. 

The  study  of  simple  perceptions  reveals  to  us  the 
law  we  seek;  it  shows  us  that  sensations  and  images 
become  organized  by  virtue  of  the  two  laws  of  sim- 
ilarity and  of  contiguity.  The  study  of  morbid 
cases,  dreams,  hallucinations,  etc.,  throws  full  light 
upon  the  subject. 

Finally,  our  theory  satisfies  the  three  conditions 
which  we  had  laid  down ;  it  introduces  only  the 
known  laws  of  the  association  of  images;  it  explains 
how  an  association  is  established  between  two 
images  by  the  operation  of  mental  laws  alone; 
finally,  it  explains  how  that  association  is  formed 
on  the  model  of  former  associations. 

All  the  preceding  discussion  may  be  reduced 
to  a  single  formula,  which  will  serve  us  as  a  defini- 
tion: 

Reasoning  is  the  establishment  of  an  association  between 
two  states  of  consciousness,  by  means  of  an  intermediate 
state  of  consciousness  which  resembles  the  first  state, 
which  is  associated  with  the  second,  and  which,  by  fusing 
itself  with  the  first,  associates  it  with  the  second. 

It  is  often  convenient  to  characterize  a  theory  in 
a  word.  Our  theory  of  reasoning  is  a  theory  of 
substitution.  We  see  in  it  the  main  term  (A)  sub- 


THE  MECHANISM  OF  REASONING.         157 

stituting  itself  for  the  middle  term  (B) — that  is  to 
say,  one  image  taking  the  place  of  another  and 
partially  identical  image.* 

*We  have  had  the  pleasure  of  meeting  a  very  analogous  theory  in  an 
article  signed  by  a  very  keen  and  original  psychologist,  Mr.  William  James. 
After  having  defined  similarity  as  the  association  of  wholes,  or  aggregates 
by  virtue  of  their  common  points,  he  observes  that  the  process  of  association 
by  similarity  closely  resembles  that  of  reasoning  properly  so  called.  Reason- 
ing, says  he  again,  consists  in  a  substitution  of  parts  of  different  wholes.  In 
a  certain  sense  it  would  be  not  at  all  too  paradoxical  to  say  that  confusion 
and  reasoning  are  two  species  of  the  same  genus.  We  identify  the  thing  in 
question  with  a  part  of  a  certain  other  whole.  In  this  common  process,  if  the 
operation  be  exact,  there  is  reasoning;  if  not  there  is  confusion. — We  quote 
from  M.  Renouvier's  analysis.  {Critique  philosophique,  1879,  P-  37°  et  seq.) 


CHAPTER  V. 

CONCLUSION. 


WE  consider  it  useful  to  distinguish  carefully 
between  the  results  of  our  analysis  and  the  conclu- 
sions which  we  shall  presently  draw  therefrom. 
We  believe  it  will  be  readily  admitted  that  in  every 
perception  there  exists  a  succession  of  three  images, 
the  first  of  which  fuses  with  the  second,  which  in 
its  turn  suggests  the  third.  The  existence  of  these 
three  images  and  their  coordination  appears  to  be 
now  and  heretofore  well  established.  These  are 
facts  which  psychologists  of  any  school  may  admit 
without  fear  of  compromising  the  theories  that  are 
dear  to  them. 

But  the  conclusions,  the  interpretations  which 
these  facts  suggest,  will  not,  in  all  probability,  meet 
with  so  ready  an  assent,  for  I  shall  presently  have 
to  touch  upon  questions  on  which  many  minds  are 
already  decided.  It  is  only  right  to  add  that  these 
interpretations  are  much  less  solidly  established 
than  their  point  of  departure. 

Under  cover  of  these  reservations  I  shall  try  to 
show  that  the  theory  of  three  images  is  applicable 
to  reasonings  of  every  kind,  and  therefore  consti- 
tutes a  general  theory  of  reasoning.  We  might 
already  affirm,  a  priori,  the  legitimacy  of  this 

158 


CONCL  US  I  ON.  1 59 

investigation ;  for  unless  it  be  maintained  that 
higher  reasoning  has  been  created  in  its  entirety,  it 
must  certainly  be  admitted  that  it  is  the  termina- 
tion of  an  ascending  evolution,  and  we  must  indicate 
from  what  lower  form  it  proceeds. 

The  reader  already  knows  that  there  is  no  de- 
cided difference  between  perception  and  logical 
reasoning;  the  two  operations  are  both  reasonings, 
transitions  from  the  known  to  the  unknown.  The 
analogy  is  so  close  that  we  were  able  to  compare 
perception  with  formal  reasoning,  and  to  show  that 
perception  contains  all  the  essential  elements  of  a 
peripatetic  syllogism.  (See  p.  88.)  In  short,  per- 
ception and  logical  reasoning  are  only  the  two 
extremes  of  a  long  series  of  phenomena,  and  when 
we  place  ourselves  in  the  middle  of  the  series  we 
find  inferences  which  belong  to  both  at  the  same 
time.  (See  p.  70.)  Further,  we  have  shown  that  a 
kind  of  filial  relationship  exists  between  perception 
and  the  reasonings  of  conscious  logic.  Thus,  when 
we  make  systematized  anaesthesia,  which  has  been 
developed  in  a  patient  relatively  to  a  certain  person, 
gradually  disappear,  the  thing  which  appears  first  of 
all  is  the  perception  of  the  person  as  species ;  and 
it  is  only  afterwards,  by  a  kind  of  ascending  evolu- 
tion, that  the  recognition  of  the  person  as  individ- 
ual takes  place;  now,  we  know  that  recognition  is 
a  complex  operation  which  touches  closely  upon 
reasoning  properly  so  called.  All  these  reasons 
lead  to  the  belief  that  perceptive  reasoning  and 
logical  reasoning  imply  the  same  mechanism.  (See 
P-  77-) 


160        THE  PSYCHOLOGY  OF  REASONING. 

Let  us  now  examine  the  principal  objections 
which  may  be  made  to  this  argument. 

One  of  the  characteristics  which  distinguish 
logical  reasoning  from  perception  is  that  objects 
constitute  the  material  of  logical  reasoning  and 
sensations  the  material  of  perceptive  reasoning. 
There  follows  from  this  a  second  difference,  drawn 
from  the  existence  of  language;  language  being 
formed  in  order  to  name  objects  and  not  sensations, 
lends  its  support  to  logical  reasoning  and  refuses 
it  to  perception.  But  let  us  neglect  this  second 
difference,  which  is  secondary  and  derivative,  so  as 
to  devote  our  attention  to  the  first.  Let  us  be 
exact.  In  what,  from  the  psychical  point  of  view, 
do  the  terms  of  logical  reasonings  consist  ?  Some 
consist  of  general  and  abstract  ideas ;  the  others  are 
recollections  of  facts,  or  recollections  of  particular 
objects.  All  of  them  are  the  residues  of  former 
perceptions;  they  proceed  from  them  more  or  less 
directly,  but  they  all  do  proceed  from  them ;  they 
are  all  percepts. 

Up  to  the  present  we  have  considered  the  percept 
as  a  synthesis  of  sensations  and  images,  or  rather 
as  a  sort  of  microcosm ;  here  the  percept  becomes 
unity.  We  may  compare  it  to  a  chemical  radicle, 
which,  although  composed  of  atoms  of  different 
bodies,  reacts  like  a  simple  body.  The  percept  of 
a  person  or  of  a  fact,  in  which  we  saw  the  result  of 
automatic  reasoning,  becomes  a  term  in  complicated 
reasonings;  so  that  we  might  say  of  these  latter 
operations  that  therein  we  reason  on  reasonings. 

This  stated,    the  question   is  to  know  whether 


CONCLUSION.  161 

logical  reasoning  is  constructed  with  percepts  as  the 
percept  is  constructed  with  sensations.  No  good 
reason  can  be  alleged  against  this  unity  of  mental 
composition ;  we  do  not  see  why  percepts,  which 
are  groups  of  images,  should  have  other  properties 
than  isolated  images  and  sensations ;  and  we  do 
not  see  why  the  percepts  of  logical  reasoning  should 
not  associate  themselves  according  to  the  same 
processes  as  the  images  and  sensations  in  automatic 
reasoning. 

To  make  ourselves  better  understood,  let  us 
appeal  to  an  analogy.  When  we  wish  to  prove 
that  a  visual  recollection  produces  the  same  chro- 
matic effects  as  the  actual  vision,  we  experiment 
with  the  most  simple  visual  recollection,  the  repre- 
sentation of  a  colour;  we  have  seen  elsewhere 
(p.  40)  that  the  idea  of  that  colour,  of  red, 
for  example,  produces  a  consecutive  green  image. 
The  experiment  only  succeeds  by  placing  one's 
self  under  such  conditions  of  simplicity;  no 
consecutive  coloured  sensation  would  be  obtained 
by  mentally  representing  to  one's  self  a  com- 
plicated object,  such  as  a  country  landscape  or 
the  appearance  of  a  market.  Nevertheless,  we  cer- 
tainly do  not  hesitate  to  transfer  to  the  complex 
image  the  phenomenon  observed  in  the  simple 
image  of  a  colour,  and  to  make  this  phenomenon  a 
general  property  of  images.  We  believe  that  the 
generalization  is  quite  as  legitimate  in  the  case  of 
reasoning;  we  claim  that  in  this  case  again,  what 
can  scarcely  be  ascertained  directly  save  for  isolated 
images  should  be  transferred  to  complex  images; 


1 62        THE  PSYCHOLOGY  OF  REASONING. 

we  claim  that  it  should  be  admitted  that  the  terms 
of  logical  reasoning  are  connected  in  accordance 
with  the  same  laws  as  the  images  of  perceptive 
reasoning,  because  these  terms  are  groups  of  images 
which  should  have  the  same  properties  as  isolated 
images. 

But  there  is  a  still  more  decisive  reason  for  be- 
lieving that  logical  reasoning  is  constructed  on  the 
same  model  as  perception.  Our  analysis  of  percep- 
tion took  the  study  of  the  syllogism  as  its  point  of 
departure;  it  was  proposed  as  an  aim  to  find  in 
perception  again  all  the  parts  of  which  formal  rea- 
soning is  composed;  this  method  led  us  to  discover 
three  terms  and  three  propositions  in  perception, 
comparable  in  all  respects  to  the  terms  and  the 
propositions  of  the  syllogism.  From  that  dissection 
resulted  the  theory  of  three  images.  Why  should 
this  theory  not  be  applicable  with  entire  justice  to 
the  syllogism,  since  it  comes  from  it? 

We  shall  conclude  with  some  reflections  on  the 
order  in  which  the  syllogistic  propositions  are 
arranged. 

Mr.  Spencer  has  directed  a  certain  number  of 
critcisms  against  the  syllogism  in  this  connection, 
some  of  which  appear  to  us  to  be  well  founded. 
"When  I  say,"  he  says,* 

"A//  crystals  have  planes  of  cleavage; 

"•This  is  a  crystal; 

"Therefore,  this  has  a  plane  of  cleavage; 
and  when   it   is  asserted    that    this  describes  the 
mental  process  by  which  I  reached  the  conclusion, 

"Op.  fit..  Vol.  II.  p.  97. 


CONCLUSION.  163 

there  arises  the  question,  What  induced  me  to 
think  of  'all  crystals'?  Did  the  concept  'all 
crystals'  come  into  my  mind  by  a  happy  accident 
the  moment  before  I  was  about  to  draw  an  infer- 
ence respecting  a  particular  crystal?  No  one  will 
assert  such  an  absurdity.  It  must  have  been,  then, 
that  a  consciousness  of  the  particular  crystal  identi- 
fied by  me  as  such  was  antecedent  to  my  concep- 
tion of  'all  crystals.' '  That  is,  one  of  the  elements 
of  the  minor  premiss  has  suggested  one  of  the 
general  elements  of  the  major  premiss.  This 
objection  seems  to  us  very  reasonable,  as  it  leads 
us  to  transpose  the  premisses  in  the  following  way : 

This  is  a  crystal; 

A II  crystals  have  planes  of  cleavage; 

This  has  a  plane  of  cleavage. 

But  we  are  quite  unable  to  follow  Mr.  Spencer 
in  his  objections  to  this  new  arrangement  of  the 
premisses.  Why,  he  asks,  have  I  been  led  by  the 
idea  of  this  particular  crystal  to  think  of  all  crys- 
tals, and  not  of  quite  another  class?  Why?  we 
may  answer.  It  is  in  consequence  of  a  relation  of 
resemblance;  it  is  because  "this"  resembles  a  crys- 
tal, crystals  which  we  know,  and  consequently  the 
class  of  crystals.  Why,  says  Mr.  Spencer  again, 
when  I  think  of  crystals  do  I  think  of  their  planes 
of  cleavage,  and  not  of  their  angles,  their  axes,  or 
of  any  other  of  their  properties?  I  think  of  their 
planes  of  cleavage  by  reason  of  a  pre-established 
relation  of  coexistence  between  crystals  and  planes 
of  cleavage.  I  would  have  been  able  to  think  of 
any  other  attribute,  it  is  true ;  in  that  case  the 


164         THE  PSYCHOLOGY  OF  REASONING. 

conclusion  would  have  been  different,  and  instead 
of  saying  that  this  crystal  has  a  plane  of  cleavage,  I 
would  have  attributed  to  it  a  certain  other  property. 
That  is  all.  Is  a  thing  impossible  because  it  would 
have  been  possible  otherwise? 

It  is  therefore  necessary  in  every  syllogism  to 
transpose  the  premisses,  to  place  the  minor  before 
the  major,  and  to  say:  "This  is  a  crystal;  all  crys- 
tals have  planes  of  cleavage,  this  has  a  plane  of 
cleavage;"  or  again,  "Socrates  is  a  man;  all  men 
are  mortal,  therefore  Socrates  is  mortal." 

We  then  discover  a  striking  resemblance  be- 
tween perceptive  reasoning  and  logical  reasoning. 
In  the  two  cases,  the  operation  begins  in  an  asso- 
ciation of  resemblance.  The  new  arrangement  of 
the  syllogistic  propositions  is  therefore  quite  con- 
formable to  the  course  which  the  mind  follows  in 
reasoning,  since  it  reproduces  the  course  of  percep- 
tive reasoning,  that  which  constitutes  the  true  "liv- 
ing" reasoning,  while  the  reasonings  of  logical 
treatises  are  dead  reasonings,  dissected  by  the 
logicians.* 

*Thus  we  believe  that,  in  all  kinds  of  reasoning,  the  psychical  labour 
consists  essentially  of  a  fusion  of  images.  But  this  conclusion  in  no  way 
prevents  us  from  recognising  that  the  human  mind  passed  over  an  immense 
interval  on  the  day  when  it  passed  from  perceptive  and  unconscious  reason- 
ing, which  is  common  to  the  majority  of  animals,  to  logical,  conscious,  really 
scientific  reasonings,  which  are  only  accessible  to  a  very  small  number  of 
individuals.  The  superiority  of  these  latter  reasonings  depends  upon  an 
infinity  of  causes ;  they  imply  the  power  of  seizing,  beneath  apparent  con- 
trasts, real  similitudes  (for  example,  the  assimilation  of  the  mechanical  force 
of  the  wind  with  that  of  a  waterfall,  of  the  flower  with  a  transformed  leaf,  of 
the  skull  with  a  vertebra,  of  the  lightning  with  the  electric  spark,  of  respira- 
tion with  combustion,  etc.);  they  imply  a  comparison  between  the  various 
parts  of  reasoning,  which  are  all  brought  before  the  mind,  and  which  permit 
it  to  judge  if  the  conclusion  is  justified  by  its  premisses;  finally,  they  have 
the  result  not  only  of  demonstrating,  but  of  explaining,  by  bringing  the 
inferred  fact  back  under  a  more  general  law;  in  this  lies  the  superiority  of 
reasoning  over  observation,  of  the  deductive  sciences  over  the  experimental 
sciences,  of  the  geometry  of  Euclid  over  tachimetry. 


CONCLUSION.  165 

II. 

Let  us  admit  that  reasoning  is  essentially  one, 
that  the  simplest  of  inferences  is,  like  the  highest 
of  generalizations,  produced  by  a  fusion  and  a 
grouping  of  images.  From  this  general  definition 
of  reasoning  we  may  deduce  its  utility,  its  function, 
its  sphere  and  its  limits.  If  it  be  recollected  that 
images  are  fragments,  residues  of  former  sensa- 
tions; that  they  spring  from  the  same  place  as  for- 
mer sensations  have  been  received,  in  the  sensory 
centres  of  the  cerebral  surface  layers;  it  will  be 
understood  that  the  purpose  of  these  images,  in 
grouping  themselves  in  reasonings,  according  to  the 
laws  of  their  affinity,  is  to  replace  the  absent  sensa- 
tions. 

Such  is  therefore  the  function  of  reasoning;  it 
enlarges  the  sphere  of  our  sensibility,  and  extends 
it  to  all  objects  which  our  senses  cannot  know 
directly.  Thus  understood,  reasoning  is  a  supple- 
mentary sense,  which  has  the  advantage  of  being 
freed  from  those  strict  conditions  of  time  and  space, 
the  two  enemies  of  human  knowledge.  Reasoning 
is  in  turn  the  eye  which  sees,  the  hand  which 
touches  and  the  ear  which  hears. 

We  find  examples  of  these  different  functions  in 
the  study  of  perceptions. 

When,  during  the  night,  we  cross  a  room  which 
we  know,  the  impressions  of  touch  which  we  feel 
excite  visual  images  which  guide  us  among  the 
furniture  and  prevent  our  striking  ourselves  and 
stumbling.  The  mechanism  of  this  suggestion  is  a 


1 66          THE  PSYCHOLOGY  OF  REASONING. 

perception  of  touch — that  is  to  say,  a  reasoning. 
Reasoning  therefore  enables  us  in  a  manner  to 
see,  by  means  of  the  visual  image,  the  object  which 
we  touch  in  the  darkness.  And  this  internal  vision 
is  exceptionally  developed  in  somnambulists,  who 
usually  walk  with  their  eyes  closed  and  can  avoid 
obstacles  of  every  kind  by  their  hyperaesthetic  sense 
of  touch.  It  is  probable  that  if  the  somnambulist 
does  not  see  by  his  eyes,  he  sees  by  reasoning.  It 
is  reasoning  which,  from  the  depths  of  the  darkness, 
guides  him  by  means  of  an  internal  light,  formed 
by  visual  images.  Thus  we  understand  a  multi- 
tude of  improbable  feats,  how,  for  example,  a  cer- 
tain somnambulist  can  write  a  page  of  manuscript, 
read  it  over  and  correct  it  exactly,  without  the 
cooperation  of  sight. 

We  are  all  acquainted  with  the  thoroughly 
authentic  story  of  an  abbe  who  wrote  sermons  dur- 
ing his  fits  of  natural  somnambulism.*  One  day  a 
white  sheet  was  placed  on  the  page  of  manuscript 
which  he  had  just  finished,  and  he  re-read  it  on  this 
white  sheet,  making  erasures  and  corrections  here 
and  there  which  coincided  exactly  with  the  text 
below.  In  this  case  he  had  a  most  exact  visual 
image  of  the  written  page,  and  he  exteriorized  that 
image  on  the  sheet  of  paper,  thus  replacing  sight 
by  reasoning.  These  extreme  cases  give  us  the  key 
to  the  normal  state. 

It  is  more  difficult  to  demonstrate  directly  that 
logical  reasoning  is  like  a  supplementary  sense,  and 

*This  observation  is  cited  by  Bersot,  Mesmer  et  le  magnetisms  animal, 
5th  edition,  p.  247. 


CONCL  US  ION.  1 67 

that  its  purpose  is  to  give  us  an  internal  vision* 
which  protracts  the  external  vision.  In  the  syllo- 
gism the  fact  affirmed  by  the  conclusion  is  too  com- 
plex, too  abstract,  for  the  knowledge  of  it  to  appear 
comparable  to  a  sensation.  However,  many 
authors  have  maintained  an  analogous  thesis; 
Schopenhauer  said  that  the  axioms  of  geometry 
are  felt.  We  shall  no  longer  have  any  doubt  on 
this  point,  if  we  carefully  observe  what  happens 
with  hysterical  subjects,  those  species  of  voyantcs 
who  very  often  materialize  the  conclusions  of  their 
reasonings  and  make  hallucinations  out  of  them. 

One   day  we   suggest  to  W ,  who  is  in  the 

state  of  somnambulism,  that  she  should  make  a  ges- 
ture of  contempt  at  a  bust  of  Gall  placed  on  a 
neighbouring  table,  f  When  she  awakes  she  makes 
the  gesture  indicated,  and  seeking  to  explain  the 
motive  of  this  suggested  act,  which  is  for  her  spon- 
taneous and  free,  she  says:  "That  bust  is  disgust- 
ing." This  is  a  reasoned  conclusion;  but  note  that 
this  conclusion  takes  the  form  of  a  hallucination; 
the  patient  sees  the  bust  under  a  disgusting  aspect. 
M.  Fe"re  has  related  this  second  example  to  me: 
We  give,  one  day,  to  another  patient  the  hallucina- 
tion of  M.  Fere,  and  wre  make  her  believe  that  she 
is  fighting  him ;  during  this  imaginary  combat  the 
patient  strikes  his  temple  a  vigorous  blow  with  her 
fist,  which  stretches  him  on  the  ground.  On  the 
morrow  the  awakened  patient  sees  M.  Fere  enter- 

*Here  we  take,  for  the  sake  of  greater  clearness,  vision  in  place  of  all 
the  senses,  that  is  to  say  the  species  for  the  genus. 

tThe  majority  of  the  facts  which  we  describe  have  been  e.-lucidated  by 
us  in  the  course  of  researches  pursued  in  common  with  Dr.  F6r6  at  the  Sal- 
petriere  hospital. 


168    THE  PSYCHOLOGY  OF  REASONING. 

ing  the  ward,  and  she  perceives  that  he  carries  a 
black-and-blue  mark  on  his  temple.  This  mark 
was  produced  by  the  imaginary  blow  which  she  had 
given  him  on  the  previous  evening.  Here  again 
the  conclusion  of  the  reasoning  culminates  in  vision. 
The  patient  performed  the  following  unconscious 
reasoning:  I  have  given  him  an  extremely  violent 
blow  with  my  fist  on  his  temple ;  therefore  he  must 
carry  the  mark  of  it.  Hence  the  hallucination  of 
an  ecchymosis.  Upon  coming  out  of  a  phase  of 
profound  lethargy  which  has  lasted  five  minutes  at 
the  most,  a  patient  imagines  that  she  has  slept  for 
several  hours.  We  answer  that  it  is  two  o'clock  in 
the  afternoon  (it  was  really  nine  o'clock  in  the 
morning).  The  patient  immediately  feels  the  most 
acute  hunger,  and  begs  us  to  let  her  go  and  dine. 
Here  again  there  is  reasoning  (it  is  late,  therefore  I 
am  hungry)  which  produces  as  its  conclusion  a  kind 
of  organic  hallucination,  the  hallucination  of  hunger. 
The  preceding  examples  are  unpublished ;  the 
following  are  some  others  which  have  already  been 
published,  but  the  phenomenon  has  not  yet  been 
studied  from  the  point  of  view  at  which  we  place 

ourselves.     M.    Richet    suggests    to    Miss    C , 

when  she  is  in  a  trance,  that  she  is  going  on  board 
a  packet  boat,  and  that  she  is  leaving  for  New  York; 
soon  the  rolling  of  the  boat  makes  itself  felt,  the 
woman  becomes  pale,  and,  throwing  her  head  back, 
she  has  an  attack  of  real  nausea.  This  hallucina- 
tion is  produced  by  the  logical  development  which 
the  subject  causes  the  suggestion  of  a  sea  voyage 
to  undergo;  this  sickness  is  a  conclusion  from  un- 


CONCL  US  ION.  1 69 

conscious  reasoning:  I  am  on  a  packet-boat,  there- 
fore it  rolls,  therefore  I  am  sick.  M.  Richet  sug- 
gests to  one  of  his  friends  that  he  is  making  a 
balloon  ascent;  the  subject  soon  sees  a  huge  shining 
ball  in  the  distance;  it  is  the  earth,  a  sight  which 
he  suggests  to  himself,  and  which  is  again  a  deduc- 
tion from  the  original  suggestion.  When  he  pre- 
pares to  descend,  M.  Richet  suggests  that  a  piece 
of  string  is  suspended  down  to  the  earth  and  that 
the  subject  should  allow  himself  to  slide  down, 
holding  on  to  the  string  with  his  hand.  During  this 
dangerous  excursion  the  subject  stopped  suddenly, 
saying  that  the  rope  burned  his  hands.  This  is  a 
fresh  deduction  which  takes  the  hallucinatory  form. 
The  authors  who  comment  upon  facts  of  this 
kind  see  in  them  merely  a  manifestation  of  the 
association  of  ideas.  It  would  be,  they  say,  by 
association  of  ideas  that  the  patient  who  believes 
herself  to  be  on  a  steamer  experiences  nausea,  etc. 
When  they  have  pronounced  that  great  word  "asso- 
ciation," they  think  they  have  said  everything. 
That  is  a  mistake.  Although  there  are  hallucina- 
tions which  are  scarcely  anything  but  recollections 
resuscitated  under  a  sensible  form,  and  in  which 
the  mind  of  the  patient  lets  itself  be  guided  by  pre- 
established  and  completely  formed  associations, 
this  is  not  a  general  rule.  In  other  hallucinations 
it  is  quite  the  contrary;  the  patient  imagines, 
creates,  invents  an  entire  sensation,  an  object,  an 
event,  a  scene  or  a  picture,  which  is  as  new  for 
him  as  for  us,  the  witnesses.  Far  from  confining 
himself  to  associations  already  formed,  he  makes 


1 70    THE  PSYCHOLOGY  OF  REASONING. 

new  ones,  like  that  hallucinated  subject  who,  rising 
in  a  balloon,  sees  the  earth  at  his  feet,  although  up 
to  that  day  he  had  never  made  an  aerostatic  ascent. 
Now,  this  establishing  of  new  associations,  this 
construction  of  images  according  to  a  new  plan,  is 
really  reasoning.  But  it  is  clear  that  between  rea- 
soning and  recollection  there  are  all  possible  transi- 
tions, for  reasoning  is  an  application  of  a  recollection 
to  a  datum  which  is  new  but  similar;  and  that 
which  predominates  in  the  operation  is  the  repro- 
duction of  the  recollection,  or  its  new  application,  as 
the  case  may  be. 

Here  are  some  other  facts  which  call  for  the  same 
reflections.  One  of  our  patients,  transformed  by 
suggestion  into  a  priest,  sees  himself,  upon  awaken- 
ing, dressed  in  a  cassock  which  smells  badly.  A 
patient  of  M.  Richet's,  transformed  into  the  Arch- 
bishop of  Paris,  spontaneously  sees  the  President  of 
the  Republic,  presents  his  New  Year  compliments 
to  him,  and  hears  the  President  replying  in  a  low 
voice,  " eau  btnite  de  cour"  Another,  transformed 
into  a  general,  sees  horses  and  aides-de-camp  sur- 
rounding him,  gives  orders,  reprimands,  uses  the 
telescope,  etc.  The  curious  thing  is  that  when  the 
subject  is  intelligent  and  imaginative,  the  sugges- 
tion which  is  directed  towards  him  produces,  not  an 
isolated  hallucination,  but  numerous  hallucinations 
which  form  a  picture.  I  may  refer,  in  this  connec- 
tion, to  the  examples  mentioned  by  M.  Paul  Richer 
(hallucinations  of  a  dinner  in  the  country,  of  a  fete, 
of  an  open-air  ball,  etc.)*  In  these  examples  we 

*0p.  cit.,  passim. 


CONCL  USION.  1 7 1 

often  seize,  on  the  wing,  the  logical  exercise  of  the 
mind  which  draws  every  possible  deduction  from 
the  theme  imposed  upon  it.  Nothing  is  better 
suited  to  show  that  the  purpose  of  reasoning  is  to 
create  a  kind  of  logical  vision,  so  much  the  more 
striking  as  under  these  circumstances,  logical — or  in 
other  words,  hallucinatory — vision  surpasses  actual 
vision  in  intensity. 

The  same  phenomenon  is  frequently  met  with  in 
mental  alienation,  when  the  insane  person  draws 
from  a  delirious  conception  a  conclusion  which 
assumes  the  hallucinatory  form.  Everybody  knows 
the  story  of  the  man  who,  believing  himself  to  be 
a  king,  took  his  rags  for  a  royal  mantle.  A  less- 
known  case  is  that  of  a  poor  woman  who,  having 
one  evening  received,  in  a  hallucination,  a  visit 
from  her  husband,  had  thereafter  the  hallucination 
of  pregnancy.  In  this  example  one  of  the  two 
hallucinations  forms  the  premiss,  and  the  second  is 
the  conclusion,  and  each  conclusion  becomes  a  hal- 
lucination. 

In  our  opinion,  the  hypnotic  experiments  which 
we  have  just  described  give  a  most  beautiful 
demonstration  of  a  phenomenon  which  is  doubtful 
and  almost  altogether  elusive  in  the  normal  state. 

We  are  inclined  to  believe  that  ordinary  reason- 
ings culminate  in  a  similar  but  less  intense  vision. 
We  throw  a  stone  into  a  pond.  The  stone,  after 
having  produced  noisy  splashes  on  the  surface  of 
the  water,  falls  to  the  bottom,  while  around  ,the 
point  where  it  fell  there  forms  a  series  of  waves. 
Thence  we  infer  by  reasoning  that  another  stone 


172         THE  PSTCHOLOGT   OF  REASONING. 

thrown  into  the  same  pond,  or  into  any  mass  of 
water,  will  produce  the  same  effect  on  it.  (Bain.) 
But  in  what  does  this  conclusion  consist?  At  the 
moment  when,  just  before  flinging  the  second 
stone,  I  infer  the  effect  which  it  is  going  to  pro- 
duce, what  passes  in  my  mind?  Is  it  not  an  inter- 
nal vision  of  the  water,  of  the  noisy  splashes,  and 
of  those  concentric  waves  which  will  be  formed 
around  the  disturbed  point?  So  the  purpose  of 
every  reasoned  conclusion  appears  to  me  to  be  to 
make  us  see,  by  the  mind's  eye,  the  object  or  the 
fact  which  the  conclusion  affirms.  The  person  who 
reasons,  meditates  in  order  to  behold  within 
himself,  in  a  sort  of  magic  lantern,  the  images 
which  pass  and  the  pictures  which  are  formed. 
Reasoning  produces  a  kind  of  logical  vision  which 
fills  the  gaps  in  actual  vision;  it  constructs  a  new 
universe  in  our  mind  on  the  model  of  the  large.  In 
short,  such  is  the  aim  of  knowledge:  to  know,  to 
understand,  to  explain,  to  know  the  why  and  the 
how  of  things,  all  this  culminates  in  an  act  of 
vision.  The  highest  science  is  epitomized  in  these 
simple  words :  to  see. 

Memory,  which  preserves  the  impressions  of  the 
senses,  reproduces  them  at  the  necessary  moment, 
and  localizes  them  in  their  places  in  the  picture  of 
the  past,  might  justly  be  called,  like  reasoning,  a 
supplementary  sense;  more  exactly,  memory  is  a 
vision  of  the  past,  while  reasoning  is,  in  general,  a 
prevision — that  is  to  say,  a  vision  of  the  future. 

These  conclusions  are  confirmed  by  the  previous 
experiments  on  the  consecutive  image,  which  lead 


CONCLUSION.  173 

us  to  see  in  the  visual  centre  a  retina  whose  every 
point  is  represented  in  the  peripheral  retina.  The 
expression  "the  mind's  eye"  ceases  to  be  a  meta- 
phor, and  the  field  of  the  mind  is  as  if  counterdrawn 
from  the  visual  field.  In  fact,  while  experimenting 
on  the  transferred  consecutive  image,  we  see  that 
this  image,  which,  like  a  recollection,  is  cerebral, 
has  definite  dimensions,  height  and  depth,  a  right 
side  and  a  left  side,  and  a  position  in  the  field  of 
vision,  properties  which  prove  to  be  common  to  all 
the  images  of  the  mind,  and  render  the  relation 
between  the  image  and  the  sensation  still  more 
intimate. 

III. 

Three  images  which  succeed  each  other,  the 
first  evoking  the  second  by  resemblance,  and  the 
second  suggesting  the  third  by  contiguity — that  is 
reasoning.  Submit  any  reasoning  to  analysis,  and 
you  will  find  nothing  else  at  the  bottom  of  the 
crucible.  But  it  would  be  an  error  to  believe  that 
this  process  belongs  specially  to  reasoning.  Far 
from  it.  We  meet  it  in  all  intellectual  operations; 
it  is  the  single  theme  upon  which  nature  has  em- 
broidered the  infinite  variations  of  our  thought. 

The  two  well-known  laws  of  the  association  of 
ideas  are  at  the  basis  of  psychology.  They  are, 
according  to  John  Stuart  Mill,  Mr.  Bain  and  Mr. 
Sully,  blended  together  in  so  intimate  a  fashion 
that  neither  of  them  can  ever  act  alone.  Let  us 
consider  a  case  of  similarity  properly  so  called,  a 
portrait  recalling  the  original ;  in  order  that  the  two 


174        THE  PSTCHOLOGT  OF  REASONING. 

similar  images  may  not  be  confounded  the  one  with 
the  other,  the  second  must  present  features  which 
are  slightly  different;  and  how  will  these  differ- 
ential characteristics  be  recalled?  By  contiguity. 
Here  we  recognize  our  three  images  and  our  two 
relations  of  resemblance  and  of  contiguity.  In 
order  that  a  relation  of  resemblance  may  be  per- 
ceived, it  must  be  followed  by  a  relation  of  conti- 
guity. Let  us  then  examine  a  case  of  contiguity. 
What  is  necessary,  asks  Mr.  Bain,  in  order  that  the 
sight  of  a  river  should  recall  its  name  to  us?  It  is 
necessary  that  the  actual  impression  made  by  the 
river  restores,  by  virtue  of  similarity,  the  former 
impression  of  the  river  to  which  the  former  impres- 
sion of  the  name  was  contiguous.  Suppose  that 
this  revival  of  the  old  idea  of  the  river  does  not  take 
place  upon  the  new  presentation,  then  the  bond  of 
contiguity  will  not  have  an  opportunity  to  enter 
into  play. 

In  this  case  we  again  find  our  three  images  and 
our  two  relations.  In  order  that  a  relation  of  con- 
tiguity may  become  known,  it  must  be  introduced 
by  a  relation  of  resemblance. 

How  does  it  happen  that  these  ideal  recollec- 
tions are  not  reasonings,  although  they  have  their 
structure?  To  tell  the  truth,  I  do  not  in  the  least 
know.  Perhaps  we  ought  to  appeal  to  what  Lewes 
called  the  attitude  of  the  mind ;  in  a  simple  associa- 
tion of  ideas  we  only  interest  ourselves  in  the  hint 
of  a  new  image ;  in  reasoning,  on  the  contrary,  we 
take  more  account  of  the  association  which  this 
new  image  contracts  with  the  preceding  one. 


CONCL  us  ION.  1 75 

The  formation  of  a  general  idea  presen-ts  the 
same  phenomenon  of  isomerism ;  we  know  that  it 
arises  from  the  union  of  several  particular  images 
which  are  welded  together  by  their  common  por- 
tions; the  total  operation  is  therefore  composed  of 
an  association  of  resemblance  followed  by  an  asso- 
ciation of  contiguity;  it  is  the  same  familiar  pro- 
cess. But  here  we  find,  between  the  general  idea 
and  reasoning,  a  logical  affinity  which  explains  this 
unity  of  composition ;  the  general  idea  is  a  reason- 
ing in  embryo;  to  generalize  any  object  is  to  affirm 
something  in  addition  to  the  result  of  a  single  ex- 
perience. The  general  idea  of  a  tree  contains  more 
elements  than  the  vision  of  an  isolated  tree;  it 
contains  an  implicit  conclusion. 

All  these  phenomena  are  like  the  first  outlines  of 
reasoning.  There  are  others,  much  more  complex, 
which  show  the  same  mental  composition.  In 
order  not  to  lose  ourselves  in  too  lengthy  develop- 
ments of  our  subject,  we  shall  remain  within  the 
limits  of  the  study  of  external  perception. 

So  far,  we  have  admitted  that  every  perception 
results  from  a  reasoning.  This  proposition  is  only 
true  in  general.  In  reality,  many  other  acts  may 
take  the  form  of  a  perception — that  is  to  say,  man- 
ifest themselves  directly  after  an  impression  of  the 
senses.  We  may  find  in  perception — first,  an  act 
of  recollection ;  second,  an  act  of  imagination. 

First. — There  is  no  well-defined  distinction  be- 
tween a  perception-recollection  and  a  perception- 
reasoning.  "To  the  psychologist,"  says  Mr.  Sully, 
"it  comes  to  very  much  the  same  thing  whether, 


176         THE  PSTCHOLOGT  OF  REASONING. 

for  example,  on  a  visit  to  Switzerland,  our  minds 
are  occupied  in  perceiving  the  distance  of  a  moun- 
tain or  in  remembering  some  pleasant  excursion 
which  we  made  to  it  on  a  former  visit.  In  both 
cases  there  is  a  reinstatement  of  the  past,  a  repro- 
duction of  earlier  experience,  a  process  of  adding 
to  a  present  impression  a  product  of  imagination — 
taking  this  word  in  its  widest  sense.  In  both  cases 
the  same  laws  of  reproduction  or  association  are 
illustrated ;  that  is  to  say,  an  association  of  resem- 
blance followed  by  an  association  of  contiguity." 
Further  on  the  author  adds  a  remark  which  proves 
how  frequent  this  phenomenon  is.  "And  our  state 
of  mind  in  recognizing  an  object  or  person  is  com- 
monly an  alternation  between  these  two  acts  of 
separating  the  mnemonic  image  from  the  percept 
and  so  recalling  or  recollecting  the  past,  and  fusing 
the  image  and  the  percept  in  what  is  specifically 
marked  off  as  recognition."* 

In  what  respect  does  a  recollection  differ  from  a 
reasoning?  This  is  difficult  to  determine.  We 
grasp  the  analogies  between  these  two  acts  much 
more  easily  than  their  differences.  All  that  the 
most  attentive  observation  teaches  us  is  that  some- 
times the  suggested  image  is  projected  and  localized 
in  the  panorama  of  the  past,  of  which  it  appears  to 
be  a  fragment,  and  sometimes  it  is  referred  to  a 
present  object,  and  throws  off  its  character  of  old- 
ness,  so  as  to  appear  actual. 

Second. — We  have  already  spoken  of  imaginary 
perceptions.  These  are  by  no  means  rare  facts, 

*Op.  cit.,  p.  235. 


CONCLUSION.  177 

mere  idle  recreations;  we  necessarily  see  in  them 
one  of  the  forms  of  that  desire  for  agreeable  illu- 
sions which  appears  to  be  inveterate  in  us,  for  we 
meet  it  in  the  adult  man,  in  the  manifestations  of 
art,  in  children,  in  their  games  (hide-and-seek,  sham 
fighting,  the  doll,  etc.),  and  even  among  young  ani- 
mals, in  their  mimic  combats.  Analysis  shows  that 
these  voluntary  illusions  are  constructed  according 
to  the  same  processes  as  correct  perceptions;  an 
association  of  resemblance  followed  by  an  associa- 
tion of  contiguity.  As  to  their  distinctive  characters, 
they  are  only  to  be  found  in  the  attitude  of  the  self 
which  accompanies  sensory  perception.  The  mind 
knows  that  it  has  to  deal  with  an  illusion ;  it  does 
not  take  it  seriously.  One  understands  that  it 
would  be  extremely  difficult  to  analyze  so  complex 
a  psychical  state. 

And  now,  how  are  we  to  explain  this  unity  of 
composition  among  intellectual  acts  which  have  such 
different  duties  to  perform?  We  believe  that  it  is 
necessary  to  introduce  the  theory  of  evolution  here. 
It  seems  to  us  probable  that  all  psychical  phenom- 
ena, so  varied  when  we  take  them  in  the  adult  civil- 
ized man,  have  sprung  from  a  common  stock,  and 
that  they  owe  to  that  their  unity  of  composition. 
But  what  can  really  be,  in  the  three  facts  which  we 
are  comparing,  the  primitive  fact  to  which  the  two 
others  may  be  referred.  It  is  that  which  is  most 
necessary  to  the  animial  in  its  struggle  for  existence : 
reasoning. 

In  fact,  reasoning  is,  as  we  have  said,  a  supple- 
mentary sense,  freed  from  the  conditions  of  time 


178         THE  PSYCHOLOGT  OF  REASONING. 

and  space.  We  have  by  means  of  reasoning  the 
sensation  of  external  objects  before  they  come  into 
contact  with  our  organism,  which  permits  us  to 
know  in  advance  what  conduct  we  must  adopt; 
whether  it  concerns  the  animal  in  pursuit  of  food, 
in  quest  of  the  female,  or  in  the  interests  of  de- 
fence, reasoning,  and  perceptive  reasoning  in  partic- 
ular, is  the  basis  of  a  preadaptation  of  the  individ- 
ual to  its  environment. 

Memory,  as  a  vision  into  the  past,  offers  less 
utility  than  reasoning;  we  have  more  frequent  need 
to  look  before  than  behind ;  it  is  a  kind  of  intellect- 
ual refinement  to  contemplate  the  things  of  the  past 
as  past,  and  without  making  them  serve  in  the 
explanation  of  present  facts.  Therefore  it  seems 
to  us  probable  that  memory  is  not  a  primitive,  but 
a  superadded  fact ;  it  has  sprung  from  reasoning  at 
a  time  when  the  struggle  for  existence  became  less 
imperious. 

The  same  may  be  said  of  imagination,  as  a 
faculty  of  creating  assemblages  of  images  which  do 
not  correspond  to  any  external  reality.  This 
faculty  must  belong  to  an  advanced  stage  of  devel- 
opment, for  it  is  not  directly  useful  in  adaptation. 
Before  taking  pleasure  in  fictions,  it  was  necessary 
to  think  of  food,  reproduction  and  defence.  There- 
fore we  must  connect  imagination  with  reasoning; 
it  is  reasoning  deviated  from  its  end,  falsified,  creat- 
ing chimeras  which  we  do  not  seek  to  rectify, 
because  they  please  us ;  thus  a  statue  is  a  fiction  of 
which  we  like  to  be  the  dupe. 

To  sum   up,    all   forms   of   mental    activity    are 


CONCL  USION.  1 79 

reducible  to  a  single  one — reasoning.  The  psy- 
chical life  is  a  continual  conclusion.  The  mind,  as 
Wundt  says,  is  a  thing  which  reasons. 

IV. 

The  preceding  theory  explains  reasoning  by  the 
properties  of  images  and  sensations,  and  by  these 
properties  alone.  It  introduces  nothing  else;  there- 
fore the  expression  "I  reason,"  which  is  employed 
so  often,  is,  taken  literally,  to  a  certain  extent 
wrong.  A  collection  of  facts  of  consciousness — the 
self  is  nothing  else^ — can  have  no  action  whatever 
on  one  fact  of  consciousness  in  particular.  It  is 
quite  as  incorrect  to  say  that  judgment  is  the  act 
by  which  the  mind  compares.  It  is  as  if  we  said 
that  chemical  combination  was  the  act  by  which 
chemistry  unites  two  bodies.  Just  as  the  combina- 
tion of  the  bodies  results  directly  from  their  proper- 
ties, so  mental  combinations,  and  reasoning  in  par- 
ticular, result  directly  from  the  properties  of  images. 

We  may  here  repeat  what  M.  Ribot  has  said  of 
the  voluntary  act:*  "The  'I  will,'  "  he  has  re- 
marked, "testifies  to  a  condition,  but  does  not  pro- 
duce it.  The  volition  that  subjective  psychologists 
have  so  often  observed,  analyzed  and  commented 
upon,  ...  is  not  the  cause  of  anything. 
The  acts  and  movements  which  follow  it  result 
directly  from  the  tendencies,  feelings,  images  and 
ideas  which  have  become  coordinated  in  the  form 
of  a  choice.  It  is  from  this  group  that  all  the  effi- 
cacy comes."  The  accuracy  of  this  point  of  view 

* Diseases  of 'the  Will  (Open  Court  Pub.  Co.,  Chicago),  p.  133. 


I  So        THE  PSTCIIOLOGT  OF  REASONING. 

is  still  more  apparent,  if  that  were  possible,  in  the 
sphere  of  reasoning.  The  idea  which  we  form  of 
reasoning,  the  attributing  of  this  operation  to  our 
self,  to  our  personality,  is  a  superadded  phenome- 
non, and  not  an  essential  part  of  the  operation. 
The  "I  reason"  is  not  a  cause,  it  is  an  effect.  It  is 
wanting  in  the  child,  in  ignorant  persons  and  in  the 
millions  of  people  who  have  never  studied  psy- 
chology. They  have  never  tried  to  give  an 
account  of  the  fact  that  they  reason,  and  of  how 
they  set  about  to  reason.  They  are  indifferent  in 
the  matter;  they  are  content  to  reason  without 
considering  how  they  do  it. 

The  intransigeants  of  psychology,  those  who 
push  everything  to  extremes,  have  maintained  that 
we  must  say,  //  reasons  in  my  brain,  as  we  say,  // 
thunders  in  the  sky.  These  expressions  are  not 
only  ridiculous,  they  are  inaccurate,  which  is  worse. 
The  formation  of  a  self,  as  the  centre  and  subject  of 
all  psychical  phenomena,  is  not  a  matter  of  conven- 
tion ;  it  is  a  natural  phenomenon,  which  is  realized 
in  every  man.  We  must  not  therefore  eliminate 
it.  M.  Richet  has  observed  that  in  experiments  on 
hypnotic  suggestion,  we  may  abolish  and  metamor- 
phose the  personality  of  the  subject  without  for  all 
that  suppressing  his  self,  which  proves  that  the  two 
things  are  distinct.  When  we  transform  the  sub- 
ject into  a  soldier,  a  dancer,  a  child,  a  bishop,  or  a 
goat,  he  adopts  the  language  and  the  gestures  of 
these  different  roles,  but  he  does  not  cease  to  say 
"I"  in  speaking  of  his  sensations  and  of  his  acts, 
to  have  a  self—  that  is  to  say,  a  kind  of  point  of 


CONCLUSION.  181 

insertion  for  all  the  sensitive  and  motor  impressions 
which  take  place  within  him.  (Richet,  La  pcrson- 
nalite'  ct  la  me1  moire  dans  le  somnambulism?,  Revue 
philosopJiique,  March,  1883.) 

So  far  nothing  has  been  said  of  the  principle  or 
postulate  which  should  be  implied,  according  to 
many  thinkers,  in  every  kind  of  reasoning,  and 
would  justify  the  passage  from  the  known  to  the 
unknown.  The  study  of  these  principles  holds  an 
important  place  in  treatises  on  logic.  For  example, 
the  postulate  of  every  induction  would  be  the 
uniformity  of  the  course  of  nature.  In  fact,  it  is 
said,  in  order  to  believe  that  what  has  been  pro- 
duced in  a  particular  case  will  be  reproduced  in  all 
similar  cases,  it  is  necessary  to  believe  previously 
that  "  there  are  such  things  in  nature  as  parallel 
cases;  that  what  happens  once,  will,  under  a  suffi- 
cient degree  of  similarity  of  circumstances,  happen 
again,  and  not  only  again,  but  always."* 

It  was  long  ago  answered  that  the  uniformity  of 
the  laws  of  nature  was  not  taught  us  by  a  super- 
natural revelation;  it  is  a  very  complex  piece  of 
knowledge,  which  is  wanting  in  the  majority  of 
men,  and  which,  among  those  who  possess  it,  is 
formed  late,  by  a  slow  accumulation  of  partial 
inductions.  To  postulate  the  result  of  a  particular 
induction,  which  is  neither  constant,  nor  elemen- 
tary, nor  primitive,  as  the  foundation  of  our  induc- 
tions would  therefore  be  to  reason  in  a  circle. 

The  real  foundation  of  reasoning  must  be 
sought  in  the  psychical  law  which  governs  it.  The 

*John  Stuart  Mill,  Logic,  Book  III,  Chap.  HI, 


1 82    THE  PSYCHOLOGY  OF  REASONING. 

organization  of  our  intelligence  is  so  arranged  that 
when  the  premisses  of  a  reasoning  are  stated,  the 
conclusion  results  from  them  with  the  necessity  of 
a  reflex  action.  In  other  words,  we  reason  because 
we  have  in  our  brain  a  machine  for  reasoning.  The 
legitimacy  of  our  inferences  has  not  a  rational  basis ; 
it  is  not  proved,  for  every  demonstration  presup- 
poses the  legitimacy  of  the  reasoning.  This  is  a 
common  sense  truth. 

Let  us  be  more  precise;  in  reasoning,  the 
primary  role  belongs  to  the  images ;  it  is  the  images 
which  arrange  themselves,  in  reasoning,  by  virtue 
of  the  properties  which  they  manifest  when  they  are 
brought  before  the  mind ;  it  is  they  which  sponta- 
neously form,  to  our  internal  sight,  the  picture  of 
the  external  world. 

This  conception  is  directly  derived  from  the 
facts  which  fill  this  book.  We  have  shown  that 
similarity  is  a  property  of  images,  and  we  have  said 
with  M.  Pilon  that  we  must  distinguish  between 
the  action  of  resemblance  and  the  perception  of 
resemblance.  (Seep.  127.)  From  this  important 
distinction  it  follows  that  the  suggestion  of  similar 
images  is  a  primary  fact  of  automatism;  that  the 
union  and  fusion  of  similar  images  into  a  generic 
image  is  a  second  fact  of  automatism ;  and  that  the 
organization  of  similar  images  into  reasoning  is  a 
third  fact  of  automatism.  In  all  these  cases  the 
self  only  intervenes  when  the  work  is  finished.  Just 
as  "the  resemblance  between  two  images  is  only 
perceived  after  their  suggestion"  (Pilon),  so  the 


CONCL  US  I  ON.  1 83 

reasoning  which  they  form  in  becoming  organized  is 
only  perceived  after  its  formation. 

If  it  were  necessary  to  make  use  of  a  comparison 
in  order  to  describe  the  mechanism  of  reasoning,  we 
would  mention  those  flowers  which  are  formed  dur- 
ing frost  on  the  window  panes  of  rooms.  Let  us 
thaw  them  with  our  breath  and  then  observe  the 
regelation  of  the  liquid  layer.  While  crystallization 
is  taking  place  round  a  first  crystal  "you  notice  one 
feature  which  is  perfectly  unalterable,  and  that  is, 
angular  magnitude.  The  spiculae  branch  from  the 
trunk,  and  from  these  branches  others  shoot ;  but 
the  angles  enclosed  by  the  spiculae  are  unalter- 
able."* Just  as  these  crystallizations  are  produced 
by  the  forces  inherent  in  each  of  the  molecules,  so 
reasoning  is  produced  by  the  properties  inherent  in 
each  of  the  images;  just  as  crystallization,  in  its 
oddest  eccentricities,  always  observes  a  certain 
angular  value,  so  reasoning,  true,  false  or  insane, 
always  obeys  the  laws  of  resemblance  and  of  conti- 
guity. 

This  being  admitted,  reasoning  may  become 
unconscious  without  our  being  obliged  to  infer  a 
profound  change  in  the  phenomena.  When  it  is 
admitted  that  reasoning  results  from  a  faculty  of 
the  soul,  is  there  any  more  embarrassing  question 
than  to  explain  the  unconsciousness  of  certain 
reasonings?  From  our  point  of  view  nothing  is 
more  simple.  Reasoning  is  a  synthesis  of  images. 
Images  are  the  psychical  part  of  a  psycho-physio- 
logical whole ;  if  they  are  wanting,  the  physiological 

*Tyndall,  Light,  p.  101;  American  Ed.,  p.  104. 


184    THE  PSYCHOLOGY  OF  REASONING. 

process  remains;  it  alone  is  essential,  and  it  is  suffi- 
cient. The  physiological  mechanism  acts,  as  if  it 
were  accompanied  by  its  epiphenomenon,  con- 
sciousness; it  does  its  work  noiselessly,  and  as 
surely  arrives  at  the  final  result. 

We  are  not  able  to  describe  this  physiological 
process.  Here  we  are  still  in  the  region  of  hypoth- 
eses; we  append  a  schema  which  will  serve  merely 
to  fix  our  ideas.  To  limit  the  question,  let  us  take 
the  visual  perception  of  a  particular  object. 

Every  perception  implies  anterior  states  which 
are  preparatory  to  it.  In  order  that  we  should  be 
able  to  perceive  the  object  which  is  before  us,  to 
recognize  its  nature,  its  use,  etc.,  it  is  necessary 
that,  through  preceding  experiences,  we  should  have 
associated  in  our  mind  the  visual  image  of  this 
object  or  of  another  of  the  same  kind,  with  the  train 
of  images  of  all  sorts  which  constitute  our  knowl- 
edge of  it.  How  shall  we  express  the  product  of 
these  anterior  experiences  in  physiological  terms? 
Images  have  the  same  cerebral  seat  as  sensations ; 
we  may  suppose  that  each  of  them  results  from  the 
excitation  of  such  and  such  a  group  of  cells  taken 
in  the  sensory  centres  of  the  surface  layers.  Let  us 
denote  the  visual  image  of  the  object  by  a*B ;  these 
two  letters  will  represent  the  two  cells  of  the  centre 
of  vision  which  are  supposed  to  vibrate  when  we 
imagine  the  object  visually;  by  C  D  E  F  G  H 
we  shall  denote  the  cells  which  serve  as  substra- 
tum to  the  other  images  of  the  object,  tactile, 
muscular,  etc.,  images. 


C  ONCL  US  ION.  1 85 

So  far  the  hypothesis  raises  no  difficulties.  But 
we  have  so  far  eliminated  an  essential  element,  the 
relations.  Psychological  analysis  proves  that  a 
bond  of  association  exists  between  the  different 
images  of  an  object;  it  is  this  bond  which  gives  the 
group  its  coherence  and  its  unity,  and  which  enables 
one  of  the  attributes  of  an  object  to  suggest  the 
others,  as  when  the  voice  of  a  person  recalls  his 
countenance.  How  can  we  translate  this  associa- 
tion physiologically?  How  are  two  impressions,  of 
sight  and  hearing  for  instance,  bound  together  in 
the  brain?  For  that  to  be  the  case  it  is  necessary 
that  they  be  not  restricted,  the  one  to  the  visual 
centre  and  the  other  to  the  auditory  centre.  It  has 
been  assumed  that  when  two  groups  of  cells — the 
substratum  of  two  images — are  excited  at  the  same 
time,  the  nervous  wave  circulates  from  one  group 
to  the  other  through  those  communicating  fibres 
which  are  so  numerous  in  the  brain.  So,  as  M. 
Fouillee  says,  do  the  two  undulations  produced  in 
a  mass  of  water  by  two  stones  dropped  at  a  small 
distance  apart  come  to  meet  each  other.  From 
this  fact  it  follows  that  the  path  between  the  two 
groups  of  cells  under  consideration  is  rendered 
easier  for  future  waves,  and  that  when,  later  on, 
one  of  the  two  groups  will  be  alone  excited,  the 
current  leaving  it  will  follow  that  way  in  preference 
to  any  other,  as  being  the  line  of  least  resistance. 
(Spencer.)  In  this  way  the  elementary  fact  of  the 
association  of  ideas  has  been  translated  into  physi- 
ological terms.  It  has  been  said  that  groups  of 


1 86        THE  PSYCHOLOGY  OF  REASONING. 

cells  excited  at  the  same  time  are  united  by  dynam- 
ical associations  (Ribot),  or,  again,  form  a  single 
and  individual  clicht,  (Taine.)  Thus  in  our 
example  a  dynamical  association  exists  between  the 
cells  #B  corresponding  to  the  visual  image  of  the 
object,  and  the  cells  C  D  E  F  G  H  corresponding 
to  the  mechanical  sensations  which  the  object  gives 
when  it  is  taken  hold  of. 

Let  us  add  one  touch  more,  and  the  hypothesis 
is  complete.  We  have  not  spoken  yet  of  the 
excitative  sensation  which  must  cause  this  associa- 
tion of  cells  to  vibrate.  Analysis  has  taught  us 
that  in  external  perception  the  sensation  always 
resembles  in  part  the  first  image  which  it  evokes — 
that  is  to  say,  the  anterior  vision  or  visual  recollec- 
tion of  the  same  object,  which  we  have  denoted  by 
rtB.  We  may  therefore  denote  the  cells  which  will 
vibrate  under  the  influence  of  the  actual  vision  by 
the  letters  Aa.  The  small  a  in  this  formula  is  the 
name  of  the  element  common  to  the  actual  vision 
and  to  the  past  vision;  for  we  know  that  the  psy- 
chical quality  of  resemblance  has  identity  of  seat 
as  its  physiological  correlative. 

When  the  vision  begins,  the  nervous  wave,  after 
having  traversed  the  group  of  cells  Aa,  passes  into 
the  group  «B,  by  means  of  the  cellular  junction 
afforded  to  it  by  the  cell  a.  In  psychological  terms, 
the  vision  of  the  object  first  of  all  recalls,  by  simil- 
arity, its  visual  recollection.  Then  the  nervous 
wave  continues  its  path  by  means  of  the  preestab- 
lished  dynamical  associations,  and  it  spreads  itself 


CONCL  US  I  ON.  1 87 

among  the  groups  of  cells  denoted  by  C  D  E  F 
G  H ;  at  the  same  time  the  recollection  of  all  the 
old  experiences  rises  in  the  mind;  this  wave  of 
images  becomes  associated  with  the  vision  of  the 
moment,  and  the  psychical  synthesis  is  formed. 

Certainly  such  a  conception  of  the  action  of  the 
nerve  centres  is  a  true  hypothesis;  we  have  no 
means  whatever  of  observing  what  occurs  in  the 
brain  of  a  thinking  man.  All  that  we  can  affirm  is 
that  reasoning  might  be  effected  by  the  mechanism 
described,  for  our  neuro-physiological  hypothesis  is 
traced  from  the  subjective  analysis  of  reasoning. 
Thus  reasoning  might  be  defined  from  the  physio- 
logical point  of  view  as  the  continuation  of  a  process 
whose  first  phase  (the  excitation  of  the  cells  Aa)  is 
the  only  one  which  corresponds  to  an  external  stim- 
ulant. This  is  the  counterpart  of  the  psychological 
definition :  reasoning  is  an  extension  of  experience. 

We  leave  to  the  reader  the  care  of  deciding 
whether  this  mechanical  theory  removes  all  activity 
from  the  mind,  so  as  to  reduce  it  to  a  purely  passive 
state.  This  is  a  reproach  which  has  often  been 
made  against  the  English  school,  which  tries  to 
explain  all  the  phenomena  of  the  mind  by  the  laws 
of  association.  But  to  what  extent  is  this  reproach 
well-founded?  Images  are  not  by  any  means  dead 
and  inert  things;  they  have  active  properties;  they 
attract  each  other,  become  connected  and  fused  to- 
gether. It  is  wrong  to  make  the  image  into  a 
photographic  stereotype,  fixed  and  immutable.  It  is 
a  living  element,  something  which  is  born,  some- 


l88        THE  PSrCIIOLOGT  OF  REASONING. 

thing  which  transforms  itself,  and  which  grows 
like  one  of  our  nails  or  our  hairs.  Mental  activity 
results  from  the  activity  of  images  as  the  life  of  the 
hive  results  from  the  life  of  the  bees,  or,  rather,  as 
the  life  of  an  organism  results  from  the  life  of  its 
cells. 

THE  END. 


INDEX. 


Achromatopsia,  34. 
Agraphia,  25. 
Alcoholic  delirium,  134. 
Ampere,  121. 

Anaesthesia,  systematised.73,76. 
Aphasia,  motor,  25. 
Arisiotle,  i,  87. 
Association,  laws  of,  92. 
Auditifs,  23. 

Baillarger,  48. 

Bain,  Alexander,  4,   41,   43,  96, 

119,  144,  172,  173,  174. 
Ball,  61. 
Beclard,  44. 
Bersot,  166. 
Beyle,  115. 
Binet,  26,  43,  60,  73. 
Blindness,  verbal,  26. 
Boole,  152. 
Brochard,  2,  90,  129. 
Brewster,  61. 

Charcot,  17,  27,  31. 
Chromatic  contrast,  39. 
Circle  of  sensation,  105. 
Clifford,  112. 
Color  blindness,  34. 
Coloured  hallucinations,  35, 
Composite  portraits,  116. 


Consciousness,  intermediate 

state  of,  139,  148. 
Contrast,  chromatic,  39. 
Cycle,  visual,  114. 

Da  Vinci,  Leonardo,  136. 
De  Boismont,  Brierre,  53. 
Delboeuf,  116. 
Delirium,  alcoholic,  134. 
Diplopia,  hallucinatory,  62. 

Euler,  i. 

Evolution,  theory  of,  177. 
Experiment,  mirror,  66. 
Experiments  in  hypnotism,  31. 

Fe*re\  26,  39,  37,  40,  42,  61,  63, 

73.  167. 
Fouillee,  185. 
Fusion  of  similar  images,  the, 

"3- 

Fusion,  laws  of,  108. 

Galton,  ii,  15,  24,  25.  113,  116, 

118. 
Genesis  of  external  perception, 

129. 
Goethe,  114. 

Hallucinations,    coloured,     35 ; 
hypnotic,    56 ;    induced.    32 ; 


igo 


THE  PSYCHOLOGY  OF  REASONING. 


suggested,    33 ;    toxic,    135 ; 

visual,  38. 

Helmboltz,  8,  39,  50,  88,  143. 
Hemi-anaesthesia,  34. 
Henslow,  Rev.  George,  113. 
Huxley,  116. 
Hypnotism,  experiments  in,  31. 

Illusions,  of  the  senses,  5,  60, 
89,  130;  passive,  89;  volun- 
tary, 177. 

Images,  consecutive,  44,  172  ; 
consecutive  and  real,  com- 
pared, 49 ;  denned,  8,  31 ;  dif- 
ferent kinds  of,  13  ;  generic, 
116;  localisation  of  the,  37; 
motor,  24  ;  physiology  of  the, 
31  ;  physiological  properties 
of,  43 ;  psychological  nature 
of,  10  ;  seat  of,  31  ;  the  fu- 
sion of  similar,  113  ;  theory 
of  three,  158  ;  sensations  and, 
combination  of,  68. 

Imagination,  178. 

Indifferents,  14. 

Induced  hallucinations,  32. 

James,  William,  24,  157. 
Janet,  Paul,  2,  4. 

Lachelier,  5. 

Laird,  Louis,  140. 

Lewes,  123. 

Localisation  of  the  image,  37. 

Londe,  59. 

Lotze,  120. 

Magnan,  115,  135. 

Maury,  116,  129. 

Memory,  172,  178. 

Mill,   John  Stuart,  r,  2,  79,  92, 


96,   98,    102,    144,    145,    152, 

154.  J73-  181. 
Mirror  experiment,  66. 
Moteurs,  23. 
Motor  aphasia,  25. 
Motor  image,  24. 

Nature,  uniformity  of  the  course 

of,  181. 

Nerve-fields,  theory  of,  106. 
Newton,  48. 

Oscillations,  consecutive,  42. 

Paraphrasia,  125. 

Parinaud,  39,  40,  44,  46,  47,  54. 

Paulhan,  29,  78. 

Percept,  69,  78,  160. 

Perception,  defined,  4,  8  ;'  dif- 
ferent kinds  of,  70  ;  external, 
56,  69,  8 1,  151  ;  genesis  of  ex- 
ternal, 129;  imaginary,  135; 
individual  and  generic,  73 ; 
mechanism  of,  142  ;  psycho- 
logical nature  of,  80. 

Physiology  of  the  image,  31. 

Pilon,  121,  127,  182. 

Portraits,  composite,  116. 

Pouchet,  117. 

Properties  of  images,  physiolo- 
gical. 43. 

Psychological  nature  of  images, 
10. 

Reasoning,  defined,  86,  93,  149; 
156  ;  explanation  of,  91  ;  fac- 
ulty of,  95  ;  formal,  81  ;  foun- 
dation of,  181  ;  function  of, 
165  ;  purpose  of,  171  ;  psy- 
chological mechanism  0^184  ; 
true  theory  of,  96 ;  uncon- 
scious, 80. 


1XDEX. 


191 


Renouvier,  157. 
Representations,  7. 
Retrogression,  law  of,  76. 
Ribot,   24,  76,  91,  96,  102,  124, 

179,  1 86. 

Richer,  52,  73,  82,  170. 
Richet,  168,  180. 

Schopenhauer,  167. 

Sensation,  circle  of,  105. 

Sensations  and  images,  combi- 
nation of,  68. 

Senses,  illusion  of  the,  5,  60, 
89,  130. 

Simon,  Max,  115. 

Somnambulists,  166. 

Sophism,  89. 

Spencer,  43,  79,  84,  88,  93,  97, 
119,  125,  162,  185. 

Strieker,  27. 


Suggested  hallucinations,  33. 
Sully,  70,  89,  116,  144,  173,  175. 
Syllogism,    i,    80,    84,    97,    151, 
159,  162. 

Taine,   2,   10,  u,  15,  48,60,  96, 

186. 

Toxic  hallucinations,  133. 
Trousseau,  147. 

Verbal  blindness,  26. 
Visual  cycle,  114. 
Visual  hallucination,  38. 

Weber,  103,  118. 
Wigan,  16. 

Wundt,  4,  40,  96,  121,  146,  156, 
179. 

Zootrope,  112. 


THE  OPEN  COURT 

A  MONTHLY  MAGAZINE 

Devoted  to  the  Science  of  Religion,  the  Religion  of  Science,  and 
the  Extension  of  the  Religious  Parliament  Idea. 


THE  OPEN  COURT  does  not  understand  by  religion  any  creed  or  dog- 
matic belief,  but  man's  world-conception  in  so  far  as  it  regulates  his  conduct. 

The  old  dogmatic  conception  of  Religion  is  based  upon  the  science  of  past 
ages;  to  base  religion  upon  the  matures!  and  truest  thought  of  the  present 
time  is  the  object  of  The  Open  Court.  Thus,  the  religion  of  The  Open  Courtis 
the  Religion  of  Science,  that  is,  the  religion  of  verified  and  verifiable  truth. 

Although  opposed  to  irrational  orthodoxy  and  narrow  bigotry,  The  Open 
Court  does  not  attack  the  properly  religious  element  of  the  various  religions. 
It  criticises  their  errors  unflinchingly  but  without  animosity,  and  endeavors 
to  preserve  of  them  all  that  is  true  and  good. 

The  current  numbers  of  The  Open  Court  contain  valuable  original  articles 
from  the  pens  of  distinguished  thinkers.  Accurate  and  authorised  transla- 
tions are  made  in  Philosophy,  Science,  and  Criticism  from  the  literature  of 
Continental  Europe,  and  reviews  of  noteworthy  recent  investigations  are  pre- 
sented. Portraits  of  eminent  philosophers  and  scientists  are  published,  and 
appropriate  illustrations  accompany  some  of  the  articles. 

Terms:  fi.oo  a  year;  55.  6d.  to  foreign  countries  in  the  Postal  Union. 
Single  Copies,  10  cents  (6d.). 


THE   MONIST 

A  QUARTERLY  MAGAZINE  OF 

PHILOSOPHY  AND  SCIENCE. 


THE  MONIST  discusses  the  fundamental   problems  of  Philosophy  in 
their  practical  relations  to  the  religious,  ethical,  and  sociological  questions 
of  the  day.    The  following  have  contributed  to  its  columns: 
PROF.  JOSEPH  LE  CONTE,     PROF.  G.  J.  ROMANES,        PROF.  C.  LOMBROSO, 


DR.  W.  T.  HARRIS, 
M.  D.  CONWAY, 
CHARLES  S.  PEIRCE, 
PROF.  F.  MAX  MULLER, 
PROF.  E.  D.  COPE, 
CARUS  STERNE, 
MRS.  C.  LADD  FRANKLIN, 
PROF.  MAX  VERWORN, 

PROF.  C.  LLOYD  MORGAN, 
JAMES  SULLY, 
B.  BOSANQUET, 
DR.  A.  BINET, 
PROF.  ERNST  MACH, 
RABBI  EMIL  HIRSCH, 
LESTER  F.  WARD, 
PROF.  H.  SCHUBERT, 

PROF.  E.  HAECKEL, 
PROF.  H.  HOFFDING, 
DR.  F.  OSWALD, 
PROF.  J.  DELBCEUF, 
PROF.  F.  JODL, 
PROF.  H.  M.  STANLEY, 
G.  FERRERO, 
J.  VENN, 

PROF.  FELIX  KLEIN,  DR.  EDM.  MONTGOMERY,    PROF.  H.  VON  HOLST. 

Per  copy,  50  cents;  Yearly,  $2.00.    In  England  and  all  countries  in  U.P.U. 
per  copy,  as.  6d. ;  Yearly,  93.  6d. 

CHICAGO: 

THE  OPEN  COURT  PUBLISHING  CO., 

Monon  Building,   324  Dearborn  St. 
LONDON  :  Kegan  Paul,  Trench,  Triibner  &  Company. 


CATALOGUE  OF  PUBLICATIONS 

OF  THE 

OPEN  COURT  PUBLISHING  CO. 


COPE.  E.  D. 

THE  PRIMARY  FACTORS  OF  ORGANIC  EVOLUTION. 
121  cuts.    Pp.  xvi,  547     Cloth,  82.00  net  (ios.). 

MULLER,  F.  MAX. 

THREE    INTRODUCTORY    LECTURES    ON     THE     SCIENCE    OF 

THOUGHT. 

128  pages.    Cloth,  750  (35.  6d.). 

THREE  LECTURES  ON  THE  SCIENCE  OF  LANGUAGE. 
112  pages.    2nd  Edition.    Cloth,  750  (33.  6d.). 

ROMANES.  GEORGE  JOHN. 
DARWIN  AND  AFTER  DARWIN. 

An  Exposition  of   the  Darwinian  Theory  and  a  Discussion  of  Post- 
Darwinian  Questions.    Three  Vols.,  84.00  net.     Singly,  as  follows  : 
i.  THE  DARWINIAN  THEORY.    460  pages.    125  illustrations.  Cloth,  $2.00. 
a.  POST-DARWINIAN  QUESTIONS.    Heredity  and  Utility.    Pp.338.    81.50. 
3.  POST-DARWINIAN  QUESTIONS.  Isolation  and  Physiological  Selection. 

Pp.  181.    $1.00. 
AN  EXAMINATION  OF  WEISMANNISM. 

236  pages.    Cloth,  81.00  net. 
THOUGHTS  ON  RELIGION. 

Edited  by  Charles  Gore,  M.  A.,  Canon  of  Westminster.  Third  Edition, 
Pages,  184.    Cloth,  gilt  top,  $1.25  net. 

MACH,  ERNST. 

THE  SCIENCE  OF  MECHANICS. 

A  CRITICAL  AND  HISTORICAL  EXPOSITION  OF  ITS  PRINCIPLES.  Translated 

byT.  J.  McCoRMACK.  250  cuts.  534  pages.  %  m.,  gilt  top.  $2.50  (i2s.6d.). 
POPULAR  SCIENTIFIC  LECTURES. 

Third  Edition.  415  pages.   59  cuts.   Cloth,  gilt  top.    Net,  $1.50  (75.  6d.). 
THE  ANALYSIS  OF  THE  SENSATIONS. 

Pp.  208.    37  cuts.    Cloth,  $1.25  net  (6s.  6d.). 

LAGRANGE,  J.  L. 

LECTURES  ON  ELEMENTARY  MATHEMATICS. 

With  portrait  of  the  author.    Pp.  172.    Price,  $1.00  net  (55.). 

DE  MORGAN,  AUGUSTUS. 

ON  THE  STUDY  AND  DIFFICULTIES  OF  MATHEMATICS. 

New  Reprint  edition  with  notes.    Pp.  viii+288.    Cloth,  $1.25  net  (55.). 

SCHUBERT,  HERMANN. 

MATHEMATICAL  ESSAYS  AND  RECREATIONS. 
Pp.  149.    Cuts,  37.    Cloth,  750  net  (35.  6d.). 

HUC  AND  GABET,  MM. 

TRAVELS  IN  TARTARY,  THIBET  AND  CHINA. 

(1844-1846.)    Translated  from  the  French  by  W.  Hazlitt.    Illustrated 
with  loo  engravings  on  wood,     z  vols.     Pp.  28  +  660.     Cl.,  J2.oo  (ios.). 

CORNILL,  CARL  HEINRICH. 
THE  PROPHETS  OF  ISRAEL. 

Popular  Sketches  from  Old  Testament  History.    Pp.,  200.    Cloth,  Ji.oo 

net  (55.). 
HISTORY  OF  THE  PEOPLE  OF  ISRAEL. 

Pp.  vi  +  325.    Cloth,  $1.50  (?s.  6d.). 

POWELL.   T.  W. 

TRUTH  AND  ERROR;  or,  the  Science  of  Intellection. 
Pp.  423.    Cloth,  $1.75  (75.  6d.). 


WAGNER,  RICHARD. 

A  PILGRIMAGE  TO  BEETHOVEN. 

A  Story.   With  portrait  of  Beethoven.  Pp.  40.  Boards,  500  net  (as.  6d.). 

HUTCHINSON,  WOODS. 

THE  GOSPEL  ACCORDING  TO  DARWIN. 
Pp.  xii  +241.     Price,  $1.50  (6s.). 

FREYTAG,   GUSTAV. 

THE  LOST  MANUSCRIPT.     A  Novel. 

2  vols.   953  pages.    Extra  cloth,  $4.00  (2is).    One  vol.,  cl.,  Ji.oo  (55.). 
MARTIN  LUTHER. 

Illustrated.    Pp.  130.    Cloth,  Ji.oo  net  (55.). 

TRUMBULL,  M.   M. 

THE  FREE  TRADE  STRUGGLE  IN  ENGLAND. 

Second  Edition.    296  pages.     Cloth,  750  (35.  6d.}. 
WHEELBARROW  :  ARTICLES  AND  DISCUSSIONS  ON  THE  LABOR  QUESTION. 

With  portrait  of  the  author.    303  pages.     Cloth,  $1.00  (53.). 

GOETHE  AND  SCHILLER'S  XENIONS. 

Translated  by  Paul  Carus.     Album  form.     Pp.  162.    Cl.,  $1.00(55.). 

OLDENBERG,  H. 

ANCIENT  INDIA:    ITS  LANGUAGE  AND  RELIGIONS. 
Pp.  100.    Cloth,  soc  net  (2S.  6d.). 

CARUS.  PAUL. 

THE  ETHICAL  PROBLEM. 

Second  edition,  revised  and  greatly  enlarged.   351  pages.    Cloth,  $1.25 

(6s.  6d.). 
FUNDAMENTAL  PROBLEMS. 

Second  edition,  enlarged  and  revised.    372pp.    Cl.,  $1.50  (75.  6d.). 
HOMILIES  OF  SCIENCE. 

317  pages.    Cloth,  Gilt  Top,  $1.50  (73.  6d.). 
THE  IDEA  OF  GOD. 

Fourth  edition.    32  pages.    Paper,  150  (gd.). 
THE  SOUL  OF  MAN. 

With  153  cuts  and  diagrams.    458  pages.    Cloth,  $3.00  (153.). 
TRUTH  IN  FICTION.    TWELVE  TALES  WITH  A  MORAL. 

White  and  gold  binding,  gilt  edges.     Pp.  in.     fi.oo  (ss.). 
THE  RELIGION  OF  SCIENCE. 

Second,  extra  edition.    Pp.  103.    Price,  soc  net  (is.  6d.). 
PRIMER  OF  PHILOSOPHY. 

240  pages.     Second  Edition.     Cloth,  $1.00  (53.). 
THE  GOSPEL  OF  BUDDHA.     According  to  Old  Records. 

Fifth  Edition.   Pp.  275.   Cloth,  $1.00  (55.).    In  German,  $1.25  (6s.  6d.). 
BUDDHISM  AND  ITS  CHRISTIAN  CRITICS. 

Pages,  311.    Cloth,  $1.25  (6s.  6d.). 
KARMA.    A  STORY  OF  EARLY  BUDDHISM. 

Illustrated  by  Japanese  artists.    Crfipe  paper,  750  (33.  6d.). 
NIRVANA:  A  STORY  OF  BUDDHIST  PSYCHOLOGY. 

Japanese  edition,  like  Karma.    $1.00  (45.  6d.). 

LAO-TZE'S  TAO-TEH-KING. 

Chinese-English.    With  introduction,  transliteration,  Notes,  etc.   Pp. 
360.    Cloth,  $3.00  (155.). 

GARBE,   RICHARD. 

THE  REDEMPTION  OF  THE  BRAHMAN.    A  TALE  OF  HINDU  LIFE. 

Laid  paper.     Gilt  top.    96  pages.     Price,  750  (35.  6d.), 
THE  PHILOSOPHY  OF  ANCIENT  INDIA. 
Pp.  89.    Cloth,  soc  net  (as.  6d.). 

HUEPPE,  FERDINAND. 

THE  PRINCIPLES  OF  BACTERIOLOGY. 

28  Woodcuts.    Pp.  467  +  x.    Price,  $1.75  net  (95.). 


The  Religion  of  Science  Library. 

A  collection  of  bi-monthly  publications,  most  of  which  are  reprints  of 
books  published  by  The  Open  Court  Publishing  Company.  Yearly,  $1.50. 
Separate  copies  according  to  prices  quoted.  The  books  are  printed  upon 
good  paper,  from  large  type. 

The  Religion  of  Science  Library,  by  its  extraordinarily  reasonable  price 
will  place  a  large  number  of  valuable  books  within  the  reach  of  all  readers. 

The  following  have  already  appeared  in  the  series: 

No.  i.   The  Religion  of  Science.     By  PAUL  CARUS.     250  (is.  6d  ). 

2.  Three  Introductory  Lectures  on  the  Science  of  Thought,     By  F.  MAX 

MULLKR.     250  (is.  6d.). 

3.  Three  Lectures  on  the  Science  of  Language.  F.  MAX  MOLLER.  25C(is.6d.). 

4.  The  Diseases  of  Personality.     By  TH.  RIBOT.    250  (is.  6d.). 

5.  The  Psychology  of  Attention.     By  TH.  RIBOT.    250  (is.  6d.). 

6.  The  Psychic  Life  of  Micro- Organisms.     By  ALFRED  BINET.     250  (is.  6d.). 

7.  The  Nature  of  the  State.     By  PAUL  CARUS.     150  (gd.). 

8.  On  Double  Consciousness.     By  ALFRED  BINET.     150  (gd.). 
g.  Fundamental  Problems.     By  PAUL  CARUS.     joe  (as.  6d.). 

10.  The  Diseases  of  the  Will.     By  TH.  RIBOT.    250  (is.  6d.). 

11.  The  Origin  of  Language.    By  LUDWIG  NOIRE.     150  (gd.). 

12.  The  Free  Trade  Struggle  in  England.     M.  M.  TRUMBULL.    250  (is.  6d.). 

13.  Wheelbarrow  on  the  Labor  Question.     By  M.  M.  TRUMBULL.   350  (2s.). 

14.  The  Gospel  of  Buddha.     By  PAUL  CARUS.     350(28.). 

15.  The  Primer  of  Philosophy.    By  PAUL  CARUS.    250  (is.  6d.). 

16.  On  Memory,  and  The  Specific  Energies  of  the  Nervous  System.     By  PROF. 

EWALD  HERING.     150  (gd.). 

17.  The  Redemption  of  the  Brahman.    A  Tale  of  Hindu  Life.     By  RICHARD 

GARBE.    250  (is.  6d.). 

18.  An  Examination  of  Weismannism.     By  G.  J.  ROMANES.    350  (2S.). 
ig.  On  Germinal  Selection.     By  AUGUST  WEISMANN.     250  (is.  6d.). 

20.  Lovers  Three  Thousand  Years  Ago.     By  T.  A.  GOODWIN.     150  (gd.). 

21.  Popular  Scientific  Lectures.     By  ERNST  MACH.     soc  (as.  6d.). 

22.  Ancient  India  :  Its  Language  and  Religions.    By  H.  OLDENBERG.    250, 

(is.  6d.). 

23.  The  Prophets  of  Israel.     By  PROF.  C.  H.  CORNILL.     250  (i.  6d.). 

24.  Homilies  of  Science.    By  PAUL  CARUS.    350  (as.). 

25.  Thoughts  on  Religion.     By  G.  J.  ROMANES.     500  (as.  6.d). 

26.  The  Philosophy  of  Ancient  India.  By  PROF.  RICHARD  GARBE.  25c(is.6d.). 

27.  Martin  Luther.    By  GUSTAV  FREYTAG.    250  (is.  6d.). 

28.  English  Secularism.    By  GEORGE  JACOB  HOLYOAKE.    250  (is.  6d.). 
2g.  On  Orthogenesis.     By  TH.  EIMER.    250  (is.  6d.). 

30.  Chinese  Philosophy.    By  PAUL  CARUS.     250  (is.  6d.). 

31.  The  Lost  Manuscript.    By  GUSTAV  FREYTAG.    6oc  (35.). 

32.  A  Mechanico-Physiological  Theory  of  Organic  Evolution.    By  CARL  VON 

NAEGELI.    150  (gd.). 

33.  Chinese  Fiction.    By  DR.  GEORGE  T.  CANDLIN.    150  (gd.). 

34.  Mathematical  Essays  and  Recreations.     By  H.  SCHUBERT.     250  (is.  6d.). 
35-  The  Ethical  Problem.    By  PAUL  CARUS.     500  (as.  6d). 


THE  OPEN  COURT  PUBLISHING  CO., 

CHICAGO  :  324  DEARBORN  STREET. 
LONDON  :  PATERNOSTER  HOUSE,  CHARING  CROSS  ROAD. 


ReturnthistnatenaLtott^ 


A     000  1 78  224     2 


